Class 10 Maths Chapter 5 Exercise 5.2 Solutions in Assamese | SEBA Class 10 Maths New Book
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| āĻ āύুāĻļীāϞāύী | 5.2 |
āĻ āϧ্āϝাāϝ় ā§Ģ : āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি — āĻ āύুāĻļীāϞāύী 5.2 (Exercise 5.2 Solutions)
• āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° n-āϤāĻŽ āĻĒāĻĻ: an = a + (n - 1)d
āĻĒ্ā§°āĻļ্āύ ā§§: āĻĻিāϝ়া āĻāĻে āϝে āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ a, āϏাāϧাā§°āĻŖ āĻ āύ্āϤ⧰ d āĻā§°ু n-āϤāĻŽ āĻĒāĻĻ an। āϤāϞ⧰ āϤাāϞিāĻাāĻāύ⧰ āĻাāϞী āĻ াāĻāϏāĻŽূāĻš āĻĒূā§°āĻŖ āĻā§°া :
(i) a = 7, d = 3, n = 8, an = ?
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 7
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 3
āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 8
āĻāĻŽি āĻাāύো āϝে, āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° n-āϤāĻŽ āĻĒāĻĻā§° āϏূāϤ্ā§°—
an = a + (n - 1)d
āĻŽাāύāϏāĻŽূāĻš āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ,
⇒ a8 = 7 + (8 - 1) × 3
⇒ a8 = 7 + (7) × 3
⇒ a8 = 7 + 21
⇒ a8 = 28
āĻāϤিāĻে, āύিā§°্āĻŖেāϝ় an = 28।
(ii) a = -18, d = ?, n = 10, an = 0
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a = -18
n = 10
an = 0
āϏূāϤ্ā§°āĻŽāϤে,
an = a + (n - 1)d
⇒ 0 = -18 + (10 - 1)d
⇒ 0 = -18 + 9d
⇒ 9d = 18
⇒ d = 18 / 9
⇒ d = 2
āĻāϤিāĻে, āύিā§°্āĻŖেāϝ় āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 2।
(iii) a = ?, d = -3, n = 18, an = -5
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
d = -3
n = 18
an = -5
āϏূāϤ্ā§°āĻŽāϤে,
an = a + (n - 1)d
⇒ -5 = a + (18 - 1)(-3)
⇒ -5 = a + (17)(-3)
⇒ -5 = a - 51
⇒ a = -5 + 51
⇒ a = 46
āĻāϤিāĻে, āύিā§°্āĻŖেāϝ় āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 46।
(iv) a = -18.9, d = 2.5, n = ?, an = 3.6
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a = -18.9
d = 2.5
an = 3.6
āϏূāϤ্ā§°āĻŽāϤে,
an = a + (n - 1)d
⇒ 3.6 = -18.9 + (n - 1)2.5
⇒ 3.6 + 18.9 = (n - 1)2.5
⇒ 22.5 = (n - 1)2.5
⇒ (n - 1) = 22.5 / 2.5
⇒ n - 1 = 9
⇒ n = 9 + 1
⇒ n = 10
āĻāϤিāĻে, āύিā§°্āĻŖেāϝ় āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 10।
(v) a = 3.5, d = 0, n = 105, an = ?
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a = 3.5
d = 0
n = 105
āϏূāϤ্ā§°āĻŽāϤে,
an = a + (n - 1)d
⇒ a105 = 3.5 + (105 - 1) × 0
⇒ a105 = 3.5 + 104 × 0
⇒ a105 = 3.5 + 0
⇒ a105 = 3.5
āĻāϤিāĻে, āύিā§°্āĻŖেāϝ় an = 3.5।
āĻĒ্ā§°āĻļ্āύ ⧍: āϤāϞ⧰ āĻĒ্ā§°āϤিāĻোā§°ে āĻļুāĻĻ্āϧ āĻāϤ্āϤ⧰āĻো āĻŦাāĻি āĻāϞিāĻā§ąা āĻā§°ু āĻাā§°āĻŖ āĻĻā§°্āĻļোā§ąা :
(i) 10, 7, 4, ... āĻāĻ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 30āϤāĻŽ āĻĒāĻĻāĻো—
(A) 97
(B) 77
(C) -77
(D) -87
āϏāĻŽাāϧাāύ āĻā§°ু āĻাā§°āĻŖ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: 10, 7, 4, ...
āĻāϝ়াāϤ,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 10
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 7 - 10 = -3
āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 30
āĻāĻŽি āĻাāύো āϝে,
an = a + (n - 1)d
⇒ a30 = 10 + (30 - 1)(-3)
⇒ a30 = 10 + (29)(-3)
⇒ a30 = 10 - 87
⇒ a30 = -77
āĻāϤ্āϤ⧰: (C) -77
(ii) -3, -1/2, 2, ... āĻāĻ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 11āϤāĻŽ āĻĒāĻĻāĻো—
(A) 28
(B) 22
(C) -38
(D) -48(1/2)
āϏāĻŽাāϧাāύ āĻā§°ু āĻাā§°āĻŖ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: -3, -1/2, 2, ...
āĻāϝ়াāϤ,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = -3
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = -1/2 - (-3) = -1/2 + 3 = (-1 + 6) / 2 = 5/2
āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 11
āĻāĻŽি āĻাāύো āϝে,
an = a + (n - 1)d
⇒ a11 = -3 + (11 - 1)(5/2)
⇒ a11 = -3 + (10)(5/2)
⇒ a11 = -3 + 5 × 5
⇒ a11 = -3 + 25
⇒ a11 = 22
āĻāϤ্āϤ⧰: (B) 22
āĻĒ্ā§°āĻļ্āύ ā§Š: āϤāϞ⧰ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāϏāĻŽূāĻšā§° āĻাāϞীāĻā§° āĻেāĻāĻাā§° āϞুāĻĒ্āϤ āĻĒāĻĻāϏāĻŽূāĻš (missing terms) āύিā§°্āĻŖāϝ় āĻā§°া :
(i) 2, [ ], 26
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 2
āϤৃāϤীāϝ় āĻĒāĻĻ (a3) = 26
āĻāĻŽি āĻাāύো āϝে, a3 = a + 2d
⇒ 26 = 2 + 2d
⇒ 26 - 2 = 2d
⇒ 2d = 24
⇒ d = 24 / 2
⇒ d = 12
āĻ
āϤāĻāĻŦ, āϞুāĻĒ্āϤ āĻĻ্āĻŦিāϤীāϝ় āĻĒāĻĻ (a2) = a + d
⇒ a2 = 2 + 12 = 14
āĻāϤ্āϤ⧰: 14
(ii) [ ], 13, [ ], 3
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻĻ্āĻŦিāϤীāϝ় āĻĒāĻĻ (a2) = 13 ⇒ a + d = 13 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
āĻāϤুā§°্āĻĨ āĻĒāĻĻ (a4) = 3 ⇒ a + 3d = 3 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
(a + 3d) - (a + d) = 3 - 13
⇒ 2d = -10
⇒ d = -10 / 2
⇒ d = -5
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + (-5) = 13
⇒ a = 13 + 5
⇒ a = 18 (āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ)
āϤৃāϤীāϝ় āĻĒāĻĻ (a3) = a + 2d
⇒ a3 = 18 + 2(-5)
⇒ a3 = 18 - 10 = 8
āĻāϤ্āϤ⧰: āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ = 18, āϤৃāϤীāϝ় āĻĒāĻĻ = 8
(iii) 5, [ ], [ ], 9(1/2)
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 5
āĻāϤুā§°্āĻĨ āĻĒāĻĻ (a4) = 9(1/2) = 19/2
āĻāĻŽি āĻাāύো āϝে, a4 = a + 3d
⇒ 19/2 = 5 + 3d
⇒ 19/2 - 5 = 3d
⇒ (19 - 10) / 2 = 3d
⇒ 9/2 = 3d
⇒ d = 9 / (2 × 3)
⇒ d = 3/2
āĻĻ্āĻŦিāϤীāϝ় āĻĒāĻĻ (a2) = a + d = 5 + 3/2 = (10 + 3) / 2 = 13/2 = 6(1/2)
āϤৃāϤীāϝ় āĻĒāĻĻ (a3) = a2 + d = 13/2 + 3/2 = 16/2 = 8
āĻāϤ্āϤ⧰: āĻĻ্āĻŦিāϤীāϝ় āĻĒāĻĻ = 6(1/2), āϤৃāϤীāϝ় āĻĒāĻĻ = 8
(iv) -4, [ ], [ ], [ ], [ ], 6
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = -4
āώāώ্āĻ āĻĒāĻĻ (a6) = 6
a6 = a + 5d
⇒ 6 = -4 + 5d
⇒ 6 + 4 = 5d
⇒ 10 = 5d
⇒ d = 2
a2 = a + d = -4 + 2 = -2
a3 = a2 + d = -2 + 2 = 0
a4 = a3 + d = 0 + 2 = 2
a5 = a4 + d = 2 + 2 = 4
āĻāϤ্āϤ⧰: -2, 0, 2, 4
(v) [ ], 38, [ ], [ ], [ ], -22
āϏāĻŽাāϧাāύ:
a2 = 38 ⇒ a + d = 38 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
a6 = -22 ⇒ a + 5d = -22 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
(a + 5d) - (a + d) = -22 - 38
⇒ 4d = -60
⇒ d = -15
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + (-15) = 38
⇒ a = 38 + 15 = 53 (āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ)
a3 = a2 + d = 38 + (-15) = 23
a4 = a3 + d = 23 + (-15) = 8
a5 = a4 + d = 8 + (-15) = -7
āĻāϤ্āϤ⧰: 53, 23, 8, -7
āĻĒ্ā§°āĻļ্āύ ā§Ē - ā§§ā§Ļ: āĻাāĻŖিāϤিāĻ āϏāĻŽাāϧাāύāϏāĻŽূāĻš :
āĻĒ্ā§°āĻļ্āύ ā§Ē: 3, 8, 13, 18, ... āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āĻোāύāĻো āĻĒāĻĻ 78?
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: 3, 8, 13, 18, ...
āĻāϝ়াāϤ,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 3
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 8 - 3 = 5
āϧ⧰ো, n-āϤāĻŽ āĻĒāĻĻ (an) = 78
āĻāĻŽি āĻাāύো āϝে, an = a + (n - 1)d
⇒ 78 = 3 + (n - 1)5
⇒ 78 - 3 = 5(n - 1)
⇒ 75 = 5(n - 1)
⇒ n - 1 = 75 / 5
⇒ n - 1 = 15
⇒ n = 15 + 1
⇒ n = 16
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 16āϤāĻŽ āĻĒāĻĻāĻো 78।
āĻĒ্ā§°āĻļ্āύ ā§Ģ: āϤāϞ⧰ āĻĒ্ā§°āϤিāĻো āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āĻĒāĻĻā§° āϏংāĻ্āϝা āύিā§°্āĻŖāϝ় āĻā§°া :
(i) 7, 13, 19, ..., 205
āϏāĻŽাāϧাāύ:
a = 7
d = 13 - 7 = 6
n-āϤāĻŽ āĻĒāĻĻ (an) = 205
an = a + (n - 1)d
⇒ 205 = 7 + (n - 1)6
⇒ 205 - 7 = 6(n - 1)
⇒ 198 = 6(n - 1)
⇒ n - 1 = 198 / 6
⇒ n - 1 = 33
⇒ n = 34
āĻāϤ্āϤ⧰: āĻĒāĻĻā§° āϏংāĻ্āϝা = 34
(ii) 18, 15(1/2), 13, ..., -47
āϏāĻŽাāϧাāύ:
a = 18
d = 15(1/2) - 18 = 31/2 - 18 = (31 - 36) / 2 = -5/2
an = -47
an = a + (n - 1)d
⇒ -47 = 18 + (n - 1)(-5/2)
⇒ -47 - 18 = (n - 1)(-5/2)
⇒ -65 = (n - 1)(-5/2)
⇒ n - 1 = (-65 × 2) / (-5)
⇒ n - 1 = 13 × 2
⇒ n - 1 = 26
⇒ n = 27
āĻāϤ্āϤ⧰: āĻĒāĻĻā§° āϏংāĻ্āϝা = 27
āĻĒ্ā§°āĻļ্āύ ā§Ŧ: 11, 8, 5, 2 ..... āĻāĻ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° -150 āϏংāĻ্āϝাāĻো āĻোāύো āĻāĻা āĻĒāĻĻ āĻš'āĻŦ āĻĒাā§°েāύে āĻĒā§°ীāĻ্āώা āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: 11, 8, 5, 2, ...
a = 11
d = 8 - 11 = -3
āϧ⧰ো, n-āϤāĻŽ āĻĒāĻĻ (an) = -150
an = a + (n - 1)d
⇒ -150 = 11 + (n - 1)(-3)
⇒ -150 - 11 = -3(n - 1)
⇒ -161 = -3(n - 1)
⇒ n - 1 = 161 / 3
⇒ n = 161/3 + 1
⇒ n = (161 + 3) / 3
⇒ n = 164 / 3
āϝিāĻšেāϤু n ā§° āĻŽাāύ āĻāĻা āϧāύাāϤ্āĻŽāĻ āĻ
āĻāĻŖ্āĻĄ āϏংāĻ্āϝা āĻš'āĻŦ āϞাāĻে āĻিāύ্āϤু āĻāϝ়াāϤ 164/3 āĻāĻা āĻāĻ্āύাংāĻļ,
āĻāϤ্āϤ⧰: -150 āϏংāĻ্āϝাāĻো āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āĻোāύো āĻĒāĻĻ āĻš'āĻŦ āύোā§ąাā§°ে।
āĻĒ্ā§°āĻļ্āύ ā§: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° 11āϤāĻŽ āĻĒāĻĻāĻো 38 āĻā§°ু 16āϤāĻŽ āĻĒāĻĻāĻো 73 āĻš'āϞে āϤাā§° 31āϤāĻŽ āĻĒāĻĻāĻো āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a11 = 38 ⇒ a + 10d = 38 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
a16 = 73 ⇒ a + 15d = 73 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
(a + 15d) - (a + 10d) = 73 - 38
⇒ 5d = 35
⇒ d = 35 / 5
⇒ d = 7
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + 10(7) = 38
⇒ a + 70 = 38
⇒ a = 38 - 70
⇒ a = -32
āĻāϤিāϝ়া, 31āϤāĻŽ āĻĒāĻĻ (a31) āύিā§°্āĻŖāϝ় āĻā§°োঁ:
a31 = a + 30d
⇒ a31 = -32 + 30(7)
⇒ a31 = -32 + 210
⇒ a31 = 178
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 31āϤāĻŽ āĻĒāĻĻāĻো 178।
āĻĒ্ā§°āĻļ্āύ ā§Ž: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāϤ 50 āĻা āĻĒāĻĻ āĻāĻে āϝাā§° āϤৃāϤীāϝ় āĻĒāĻĻāĻো 12 āĻā§°ু āĻļেāώ āĻĒāĻĻāĻো 106। 29āϤāĻŽ āĻĒāĻĻāĻো āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
āĻŽুāĻ āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 50
āϤৃāϤীāϝ় āĻĒāĻĻ (a3) = 12 ⇒ a + 2d = 12 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
āĻļেāώ āĻĒāĻĻ (a50) = 106 ⇒ a + 49d = 106 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
47d = 94
⇒ d = 94 / 47
⇒ d = 2
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + 2(2) = 12
⇒ a + 4 = 12
⇒ a = 8
āĻāϤিāϝ়া, 29āϤāĻŽ āĻĒāĻĻ (a29) āύিā§°্āĻŖāϝ় āĻā§°োঁ:
a29 = a + 28d
⇒ a29 = 8 + 28(2)
⇒ a29 = 8 + 56
⇒ a29 = 64
āĻāϤ্āϤ⧰: 29āϤāĻŽ āĻĒāĻĻāĻো 64।
āĻĒ্ā§°āĻļ্āύ ⧝: āϝāĻĻি āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āϤৃāϤীāϝ় āĻā§°ু āĻ¨ā§ąāĻŽ āĻĒāĻĻ āĻĻুāĻা āĻ্ā§°āĻŽে 4 āĻā§°ু -8 āĻšāϝ় āϤেāύ্āϤে āĻāϝ়াā§° āĻোāύāĻো āĻĒāĻĻ āĻļূāύ্āϝ āĻš'āĻŦ?
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a3 = 4 ⇒ a + 2d = 4 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
a9 = -8 ⇒ a + 8d = -8 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
6d = -12
⇒ d = -12 / 6
⇒ d = -2
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + 2(-2) = 4
⇒ a - 4 = 4
⇒ a = 8
āϧ⧰ো, n-āϤāĻŽ āĻĒāĻĻ (an) = 0
a + (n - 1)d = 0
⇒ 8 + (n - 1)(-2) = 0
⇒ -2(n - 1) = -8
⇒ n - 1 = -8 / -2
⇒ n - 1 = 4
⇒ n = 5
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 5āĻŽ (āĻĒāĻ্āĻāĻŽ) āĻĒāĻĻāĻো āĻļূāύ্āϝ āĻš'āĻŦ।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Ļ: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° 17āϤāĻŽ āĻĒāĻĻāĻো 10āϤāĻŽ āĻĒāĻĻāĻোāϤāĻৈ 7 āĻĄাāĻā§°। āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āĻļ্āύāĻŽāϤে,
a17 - a10 = 7
⇒ (a + 16d) - (a + 9d) = 7
⇒ a + 16d - a - 9d = 7
⇒ 7d = 7
⇒ d = 7 / 7
⇒ d = 1
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ d = 1।
āĻĒ্ā§°āĻļ্āύ ā§§ā§§ - ⧍ā§Ģ: āϞিāĻিāϤ āĻā§°ু āĻŦāĻšু-āĻŦিāĻāϞ্āĻĒāĻিāϤ্āϤিāĻ (MCQs) āĻĒ্ā§°āĻļ্āύāϏāĻŽূāĻš :
āĻĒ্ā§°āĻļ্āύ ā§§ā§§: 3, 15, 27, 39, ... āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āĻোāύāĻো āĻĒāĻĻ 54āϤāĻŽ āĻĒāĻĻāϤāĻৈ 132 āĻĄাāĻā§°?
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: 3, 15, 27, 39, ...
a = 3, d = 15 - 3 = 12
āĻĒ্ā§°āĻĨāĻŽে 54āϤāĻŽ āĻĒāĻĻ (a54) āĻāϞিāϝ়াāĻঁ:
a54 = a + 53d
⇒ a54 = 3 + 53(12)
⇒ a54 = 3 + 636 = 639
āĻĒ্ā§°āĻļ্āύāĻŽāϤে, āύিā§°্āĻŖেāϝ় n-āϤāĻŽ āĻĒāĻĻ (an) = a54 + 132
⇒ an = 639 + 132 = 771
⇒ a + (n - 1)d = 771
⇒ 3 + (n - 1)12 = 771
⇒ 12(n - 1) = 771 - 3
⇒ 12(n - 1) = 768
⇒ n - 1 = 768 / 12
⇒ n - 1 = 64
⇒ n = 65
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° 65āϤāĻŽ āĻĒāĻĻāĻো 54āϤāĻŽ āĻĒāĻĻāϤāĻৈ 132 āĻĄাāĻā§°।
āĻĒ্ā§°āĻļ্āύ ⧧⧍: āĻĻুāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ āĻāĻে। āϏিāĻšঁāϤ⧰ 100āϤāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āĻĒাā§°্āĻĨāĻ্āϝ 100। āϏিāĻšঁāϤ⧰ 1000āϤāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āĻĒাā§°্āĻĨāĻ্āϝ āĻিāĻŽাāύ?
āϏāĻŽাāϧাāύ:
āϧ⧰ো āĻĒ্ā§°āĻĨāĻŽ AP ā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ = A, āĻā§°ু āĻĻ্āĻŦিāϤীāϝ় AP ā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ = a।
āĻĻুāϝ়োāĻা AP ā§° āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ = d।
āĻĒ্ā§°āĻĨāĻŽ AP ā§° 100āϤāĻŽ āĻĒāĻĻ = A + 99d
āĻĻ্āĻŦিāϤীāϝ় AP ā§° 100āϤāĻŽ āĻĒāĻĻ = a + 99d
āĻĒ্ā§°āĻļ্āύāĻŽāϤে,
(A + 99d) - (a + 99d) = 100
⇒ A - a = 100 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
āĻāϤিāϝ়া, 1000āϤāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āĻĒাā§°্āĻĨāĻ্āϝ:
(A + 999d) - (a + 999d) = A - a = 100 (āϏāĻŽীāĻā§°āĻŖ ā§§ ā§° āĻĒā§°া)
āĻāϤ্āϤ⧰: āϏিāĻšঁāϤ⧰ 1000āϤāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āĻĒাā§°্āĻĨāĻ্āϝ 100 āĻš'āĻŦ।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Š: āĻিāĻŽাāύāĻা āϤিāύি āĻ
ংāĻāϝুāĻ্āϤ āϏংāĻ্āϝা 7 ā§°ে āĻŦিāĻাāĻ্āϝ?
āϏāĻŽাāϧাāύ:
7 ā§°ে āĻŦিāĻাāĻ্āϝ āϤিāύি āĻ
ংāĻāϝুāĻ্āϤ āϏংāĻ্āϝাāϏāĻŽূāĻš āĻš'āϞ: 105, 112, 119, ..., 994
āĻ āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি āĻāĻ āύ āĻā§°ে āϝ'āϤ,
a = 105, d = 7, āĻā§°ু āĻļেāώ āĻĒāĻĻ (an) = 994
an = a + (n - 1)d
⇒ 994 = 105 + (n - 1)7
⇒ 994 - 105 = 7(n - 1)
⇒ 889 = 7(n - 1)
⇒ n - 1 = 889 / 7
⇒ n - 1 = 127
⇒ n = 128
āĻāϤ্āϤ⧰: 7 ā§°ে āĻŦিāĻাāĻ্āϝ āϤিāύি āĻ
ংāĻāϝুāĻ্āϤ āϏংāĻ্āϝা 128 āĻা āĻāĻে।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Ē: 10 āĻā§°ু 250 ā§° āĻŽাāĻāϤ 4 ā§° āĻুāĻŖিāϤāĻ āĻিāĻŽাāύāĻা āĻāĻে?
āϏāĻŽাāϧাāύ:
10 āĻā§°ু 250 ā§° āĻŽাāĻāϤ 4 ā§° āĻুāĻŖিāϤāĻāϏāĻŽূāĻš āĻš'āϞ: 12, 16, 20, ..., 248
āĻāϝ়াāϤ, a = 12, d = 4, āĻā§°ু an = 248
an = a + (n - 1)d
⇒ 248 = 12 + (n - 1)4
⇒ 248 - 12 = 4(n - 1)
⇒ 236 = 4(n - 1)
⇒ n - 1 = 236 / 4
⇒ n - 1 = 59
⇒ n = 60
āĻāϤ্āϤ⧰: 4 ā§° āĻুāĻŖিāϤāĻ 60 āĻা āĻāĻে।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Ģ: n ā§° āĻি āĻŽাāύ⧰ āĻŦাāĻŦে 63, 65, 67, ... āĻā§°ু 3, 10, 17, ... āĻāĻ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি āĻĻুāĻাā§° nāϤāĻŽ āĻĒāĻĻ āĻĻুāĻা āϏāĻŽাāύ?
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āĻĨāĻŽ AP: 63, 65, 67, ...
a = 63, d = 65 - 63 = 2
n-āϤāĻŽ āĻĒāĻĻ = 63 + (n - 1)2 = 63 + 2n - 2 = 61 + 2n
āĻĻ্āĻŦিāϤীāϝ় AP: 3, 10, 17, ...
A = 3, D = 10 - 3 = 7
n-āϤāĻŽ āĻĒāĻĻ = 3 + (n - 1)7 = 3 + 7n - 7 = 7n - 4
āĻĒ্ā§°āĻļ্āύāĻŽāϤে,
61 + 2n = 7n - 4
⇒ 61 + 4 = 7n - 2n
⇒ 65 = 5n
⇒ n = 65 / 5
⇒ n = 13
āĻāϤ্āϤ⧰: n = 13 ā§° āĻŦাāĻŦে āĻĒāĻĻ āĻĻুāĻা āϏāĻŽাāύ āĻš'āĻŦ।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Ŧ: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āϤৃāϤীāϝ় āĻĒāĻĻāĻো 16 āĻā§°ু āϏāĻĒ্āϤāĻŽ āĻĒāĻĻāĻো āĻĒāĻ্āĻāĻŽ āĻĒāĻĻāĻোāϤāĻৈ 12 āĻĄাāĻā§°। āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āĻāĻে,
a3 = 16 ⇒ a + 2d = 16 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
a7 = a5 + 12
⇒ (a + 6d) = (a + 4d) + 12
⇒ a + 6d - a - 4d = 12
⇒ 2d = 12
⇒ d = 6
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + 2(6) = 16
⇒ a + 12 = 16
⇒ a = 4
āĻāϤিāĻে āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো āĻš'āĻŦ:
a, a + d, a + 2d, a + 3d, ...
⇒ 4, (4 + 6), (4 + 12), (4 + 18), ...
āĻāϤ্āϤ⧰: āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো āĻš'āϞ 4, 10, 16, 22, ...
āĻĒ্ā§°āĻļ্āύ ā§§ā§: 3, 8, 13, ..., 253 āĻāĻ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āĻļেāώ⧰ āĻĢাāϞ⧰ āĻĒā§°া 20āϤāĻŽ āĻĒāĻĻāĻো āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĻিāϝ়া āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো: 3, 8, 13, ..., 253
āϝāĻĻি āĻāĻŽি āĻĒ্ā§°āĻāϤিāĻো āĻāϞোāĻাāĻৈ āϞিāĻোঁ, āϤেāύ্āϤে—
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 253
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 3 - 8 = -5
āĻĒāĻĻā§° āϏংāĻ্āϝা (n) = 20
āĻāϤিāϝ়া āĻļেāώ⧰ āĻĒā§°া 20āϤāĻŽ āĻĒāĻĻ (āĻ
ā§°্āĻĨাā§ āĻāϞোāĻা āĻĒ্ā§°āĻāϤিāĻোā§° 20āϤāĻŽ āĻĒāĻĻ) āĻāϞিāϝ়াāĻঁ:
a20 = a + (20 - 1)d
⇒ a20 = 253 + (19)(-5)
⇒ a20 = 253 - 95
⇒ a20 = 158
āĻāϤ্āϤ⧰: āĻļেāώ⧰ āĻĢাāϞ⧰ āĻĒā§°া 20āϤāĻŽ āĻĒāĻĻāĻো 158।
āĻĒ্ā§°āĻļ্āύ ā§§ā§Ž: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āĻāϤুā§°্āĻĨ āĻā§°ু āĻ
āώ্āĻāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āϝোāĻāĻĢāϞ 24 āĻā§°ু āώāώ্āĻ āĻā§°ু āĻĻāĻļāĻŽ āĻĒāĻĻ āĻĻুāĻাā§° āϝোāĻāĻĢāϞ 44। āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻোā§° āĻĒ্ā§°āĻĨāĻŽ āϤিāύিāĻা āĻĒāĻĻ āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āĻĨāĻŽ āĻā§°্āϤāĻŽāϤে,
a4 + a8 = 24
⇒ (a + 3d) + (a + 7d) = 24
⇒ 2a + 10d = 24
⇒ a + 5d = 12 -------- (āϏāĻŽীāĻā§°āĻŖ ā§§)
āĻĻ্āĻŦিāϤীāϝ় āĻā§°্āϤāĻŽāϤে,
a6 + a10 = 44
⇒ (a + 5d) + (a + 9d) = 44
⇒ 2a + 14d = 44
⇒ a + 7d = 22 -------- (āϏāĻŽীāĻā§°āĻŖ ⧍)
āϏāĻŽীāĻā§°āĻŖ (⧍) ā§° āĻĒā§°া (ā§§) āĻŦিāϝ়োāĻ āĻā§°ি āĻĒাāĻঁ:
(a + 7d) - (a + 5d) = 22 - 12
⇒ 2d = 10
⇒ d = 5
d ā§° āĻŽাāύ āϏāĻŽীāĻā§°āĻŖ (ā§§) āϤ āĻŦāĻšুā§ąাāĻ āĻĒাāĻঁ:
a + 5(5) = 12
⇒ a + 25 = 12
⇒ a = 12 - 25 = -13
āĻĒ্ā§°āĻĨāĻŽ āϤিāύিāĻা āĻĒāĻĻ:
a1 = -13
a2 = -13 + 5 = -8
a3 = -8 + 5 = -3
āĻāϤ্āϤ⧰: āĻĒ্ā§°āĻĨāĻŽ āϤিāύিāĻা āĻĒāĻĻ āĻ্ā§°āĻŽে -13, -8 āĻā§°ু -3।
āĻĒ্ā§°āĻļ্āύ ⧧⧝: 1995 āĻāύāϤ āĻāύ্āĻĻāύাāĻ 5000 āĻāĻা āĻŦāĻā§°েāĻীāϝ়া āĻĻā§°āĻŽāĻšাāϤ āĻাāĻā§°ি āĻā§°āĻŽ্āĻ āĻā§°িāϞে āĻā§°ু āĻĒ্ā§°āϤি āĻŦāĻā§°ে 200 āĻāĻাāĻৈ āĻŦৃāĻĻ্āϧি (Increment) āϞাāĻ āĻā§°িāϞে। āĻোāύ āĻŦāĻā§°āϤ āϤেāĻঁā§° āĻĻā§°āĻŽāĻšা 7000 āĻāĻা āĻš'āĻŦ?
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āϤি āĻŦāĻā§°ā§° āĻĻā§°āĻŽāĻšাāϏāĻŽূāĻšে āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি āĻāĻ āύ āĻā§°ে: 5000, 5200, 5400, ..., 7000
āĻāϝ়াāϤ,
a = 5000
d = 200
an = 7000
an = a + (n - 1)d
⇒ 7000 = 5000 + (n - 1)200
⇒ 7000 - 5000 = 200(n - 1)
⇒ 2000 = 200(n - 1)
⇒ n - 1 = 2000 / 200
⇒ n - 1 = 10
⇒ n = 11
āĻ
āϤāĻāĻŦ, 11āϤāĻŽ āĻŦāĻā§°āϤ āϤেāĻঁā§° āĻĻā§°āĻŽāĻšা 7000 āĻāĻা āĻš'āĻŦ।
āύিā§°্āĻŖেāϝ় āĻāύ = 1995 + (11 - 1) = 2005 āĻāύ।
āĻāϤ্āϤ⧰: 2005 āĻāύāϤ āϤেāĻঁā§° āĻĻā§°āĻŽāĻšা 7000 āĻāĻা āĻš'āĻŦ।
āĻĒ্ā§°āĻļ্āύ ⧍ā§Ļ: ā§°াāĻŽāĻā§°āĻŖে āĻোāύো āĻāĻা āĻŦāĻā§°ā§° āĻĒ্ā§°āĻĨāĻŽ āϏāĻĒ্āϤাāĻšāϤ 5 āĻāĻা āϏāĻ্āĻāϝ় āĻā§°িāϞে āĻā§°ু āĻĒ্ā§°āϤি āϏāĻĒ্āϤাāĻšāϤ āϏāĻ্āĻāϝ়ā§° āϧāύ 1.75 āĻāĻাāĻৈ āĻŦāĻĸ়াāĻ āĻৈ āĻĨাāĻিāϞ। n-āϤāĻŽ āϏāĻĒ্āϤাāĻšāϤ āϤেāĻঁā§° āϏাāĻĒ্āϤাāĻšিāĻ āϏāĻ্āĻāϝ়ā§° āĻĒā§°িāĻŽাāĻŖ 20.75 āĻāĻা āĻš'āϞে n ā§° āĻŽাāύ āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āϤি āϏāĻĒ্āϤাāĻšā§° āϏāĻ্āĻāϝ়ā§° āĻĒā§°িāĻŽাāĻŖে āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি āĻāĻ āύ āĻā§°ে āϝ'āϤ,
āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) = 5
āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) = 1.75
n-āϤāĻŽ āϏāĻĒ্āϤাāĻšā§° āϏāĻ্āĻāϝ় (an) = 20.75
an = a + (n - 1)d
⇒ 20.75 = 5 + (n - 1)1.75
⇒ 20.75 - 5 = 1.75(n - 1)
⇒ 15.75 = 1.75(n - 1)
⇒ n - 1 = 15.75 / 1.75
⇒ n - 1 = 1575 / 175
⇒ n - 1 = 9
⇒ n = 9 + 1
⇒ n = 10
āĻāϤ্āϤ⧰: n ā§° āĻŽাāύ = 10।
āĻĒ্ā§°āĻļ্āύ ⧍⧧: āϏ্āϤāĻŽ্āĻ (I) ā§° āϞāĻāϤ āϏ্āϤāĻŽ্āĻ (II) āĻŽিāϞোā§ąা :
āϏ্āϤāĻŽ্āĻ (I):
P) 2, 4, 6, 8... AP āĻোā§° a5 āĻš'āĻŦ
Q) -1.2, -3.2, -5.2, -7.2... AP āĻোā§° āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ (d) āĻš'āĻŦ
R) 3, 6, 9, 12... AP āĻোā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ (a) āĻš'āĻŦ
S) 0, -4, -8, -12... AP āĻোā§° a4 - a3 ā§° āĻŽাāύ āĻš'āĻŦ
āϏ্āϤāĻŽ্āĻ (II):
1) -2
2) -4
3) 10
4) 3
āϏāĻŽাāϧাāύ:
P) 2, 4, 6, 8... ā§° a5 = a + 4d = 2 + 4(2) = 10 (āĻŽাāύ ā§Š)
Q) -1.2, -3.2... ā§° d = -3.2 - (-1.2) = -2 (āĻŽাāύ ā§§)
R) 3, 6, 9... ā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ a = 3 (āĻŽাāύ ā§Ē)
S) 0, -4, -8, -12... ā§° a4 - a3 = -12 - (-8) = -4 (āĻŽাāύ ⧍)
āĻāϤ্āϤ⧰: (B) P→3, Q→1, R→4, S→2
āĻĒ্ā§°āĻļ্āύ ⧍⧍: āϤāϞāϤ āĻĻিāϝ়া āĻোāύāĻŦোā§° āĻāĻ্āϤি āĻļুāĻĻ্āϧ āĻŦা āĻ
āĻļুāĻĻ্āϧ?
P) a1, a2, a3... āĻāĻা AP āĻš'āĻŦ āϝāĻĻিāĻšে an+1 - an, n āϏাāĻĒেāĻ্āώে āϏ্āĻŦāϤāύ্āϤ্ā§° āĻšāϝ় (āĻļুāĻĻ্āϧ)।
Q) a1, a2... AP āĻোā§° āĻŦাāĻŦে ap - aq = (p - q)d (āĻļুāĻĻ্āϧ)।
R) AP āĻোā§° āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ a āĻā§°ু āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ d āĻš'āϞে n-āϤāĻŽ āĻĒāĻĻ an = a + (n - 1)d (āĻļুāĻĻ্āϧ)।
āĻāϤ্āϤ⧰: (C) P, Q āĻā§°ু R āĻāĻাāĻāĻেāĻāĻা āϏāϤ্āϝ
āĻĒ্ā§°āĻļ্āύ ā§¨ā§Š: -1, 3, 7, 11, ... 95 AP āĻোā§° āĻŽুāĻ āĻĒāĻĻā§° āϏংāĻ্āϝা āĻāϞিāĻā§ąাā§° āϏ্āϤ⧰āϏāĻŽূāĻš āϏāĻাāĻ āϞিāĻা :
(i) -1 + 4n - 4 = 95
(ii) n = 25
(iii) an = 95
(iv) -1 + (n - 1)4 = 95
āϏāĻŽাāϧাāύ:
āĻĒ্ā§°āĻĨāĻŽ āϧাāĻĒ: an = 95 āĻĒ্ā§°āĻাāĻļ āĻā§°া (iii)
āĻĻ্āĻŦিāϤীāϝ় āϧাāĻĒ: āϏূāϤ্ā§°āϤ āĻŽাāύ āĻŦāĻšুā§ąাāĻ -1 + (n - 1)4 = 95 (iv)
āϤৃāϤীāϝ় āϧাāĻĒ: āĻŦ্ā§°েāĻেāĻ āĻাāĻি -1 + 4n - 4 = 95 (i)
āĻāϤুā§°্āĻĨ āϧাāĻĒ: āϏāĻŽাāϧাāύ āĻā§°ি n = 25 (ii)
āĻāϤ্āϤ⧰: (C) (iii)→(iv)→(i)→(ii)
āĻĒ্ā§°āĻļ্āύ ⧍ā§Ē: āĻāĻা āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° āĻĒ্ā§°āĻĨāĻŽ āϤিāύিāĻা āĻĒāĻĻ āĻ্ā§°āĻŽে b, c āĻā§°ু 2b āĻš'āϞে b āĻā§°ু c ā§° āĻ
āύুāĻĒাāϤ āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āϝিāĻšেāϤু āĻĒāĻĻ āϤিāύিāĻা (b, c, 2b) āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāϤ āĻāĻে, ∴ āϏাāϧাā§°āĻŖ āĻ
āύ্āϤ⧰ āϏāĻŽাāύ āĻš'āĻŦ।
c - b = 2b - c
⇒ c + c = 2b + b
⇒ 2c = 3b
⇒ b / c = 2 / 3
āĻāϤ্āϤ⧰: b āĻā§°ু c ā§° āĻ
āύুāĻĒাāϤ (b : c) = 2 : 3।
āĻĒ্ā§°āĻļ্āύ ⧍ā§Ģ: āϤিāύি āĻ
ংāĻāĻŦিāĻļিāώ্āĻ āĻāĻ āϧāύাāϤ্āĻŽāĻ āϏংāĻ্āϝাā§° āĻ
ংāĻ āϤিāύāĻাāĻ AP āĻāĻ āύ āĻā§°ে āĻā§°ু āϏিāĻšঁāϤ⧰ āϏāĻŽāώ্āĻি 15। āĻ
ংāĻāĻেāĻāĻা āĻāϞোāĻাāĻ āĻĒোā§ąা āϏংāĻ্āϝাāĻো āĻŽূāϞ āϏংāĻ্āϝাāĻোāϤāĻৈ 594 āĻāĻŽ। āϏংāĻ্āϝাāĻো āύিā§°্āĻŖāϝ় āĻā§°া ।
āϏāĻŽাāϧাāύ:
āϧ⧰ো āϤিāύি āĻ
ংāĻāϝুāĻ্āϤ āϏংāĻ্āϝাāĻোā§° āĻ
ংāĻ āϤিāύিāĻা āĻ্ā§°āĻŽে (a - d), a, āĻā§°ু (a + d)।
āĻĒ্ā§°āĻĨāĻŽ āĻā§°্āϤāĻŽāϤে, āĻ
ংāĻ āϤিāύিāĻাā§° āϏāĻŽāώ্āĻি = 15
⇒ (a - d) + a + (a + d) = 15
⇒ 3a = 15
⇒ a = 5
āĻ
āϤāĻāĻŦ, āĻ
ংāĻ āϤিāύিāĻা āĻš'āϞ: (5 - d), 5, āĻā§°ু (5 + d)।
āĻŽূāϞ āϏংāĻ্āϝাāĻো = 100(5 - d) + 10(5) + 1(5 + d)
= 500 - 100d + 50 + 5 + d
= 555 - 99d
āĻ
ংāĻāϏāĻŽূāĻš āĻāϞোāĻাāĻ āϞিāĻিāϞে āĻĒোā§ąা āϏংāĻ্āϝাāĻো = 100(5 + d) + 10(5) + 1(5 - d)
= 500 + 100d + 50 + 5 - d
= 555 + 99d
āĻĻ্āĻŦিāϤীāϝ় āĻā§°্āϤāĻŽāϤে,
(āĻŽূāϞ āϏংāĻ্āϝা) - (āĻāϞোāĻাāĻ āĻĒোā§ąা āϏংāĻ্āϝা) = 594
⇒ (555 - 99d) - (555 + 99d) = 594
⇒ 555 - 99d - 555 - 99d = 594
⇒ -198d = 594
⇒ d = 594 / (-198)
⇒ d = -3
āĻ
āϤāĻāĻŦ, āĻ
ংāĻ āϤিāύিāĻা āĻš'āϞ:
āĻļāϤāĻā§° āĻ
ংāĻ = 5 - (-3) = 8
āĻĻāĻšāĻā§° āĻ
ংāĻ = 5
āĻāĻāĻā§° āĻ
ংāĻ = 5 + (-3) = 2
āĻāϤ্āϤ⧰: āύিā§°্āĻŖেāϝ় āϏংāĻ্āϝাāĻো 852।
đ SEBA Class 10 Maths Chapter 5 Arithmetic Progression (āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤি) — āĻ āύুāĻļীāϞāύী 5.2 āĻāĻŽু āϏাā§°াংāĻļ
āĻেāĻŦা (SEBA) Class 10 maths chapter 5 exercise 5.2 assamese medium āϤ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° (Arithmetic Progression) n-āϤāĻŽ āĻĒāĻĻ (nth term) āύিā§°্āĻŖāϝ়ā§° āĻŦিāĻিāύ্āύ āĻাāĻŖিāϤিāĻ āύিāϝ়āĻŽ āĻā§°ু āĻŦ্āĻ¯ā§ąāĻšাā§°িāĻ āϏāĻŽāϏ্āϝাāϏāĻŽূāĻš āϏāĻŽাāϧাāύ āĻā§°া āĻšৈāĻে। āϝāĻĻি āĻāĻĒুāύি Class 10 5.2 assamese new math solution pdf download āĻŦা āϏāĻŽ্āĻĒূā§°্āĻŖ āĻĒ্ā§°āĻļ্āύোāϤ্āϤ⧰ āĻŦিāĻাā§°ি āĻāĻে, āϤেāύ্āϤে āĻāĻ āĻ āύুāĻļীāϞāύীā§° āĻŽুāĻ্āϝ āϏূāϤ্ā§° āĻā§°ু āύিāϝ়āĻŽāϏāĻŽূāĻš āĻŦুāĻি āϞোā§ąাāĻো āĻ āϤিāĻļāϝ় āĻĒ্ā§°āϝ়োāĻāύীāϝ়।
đ āĻ āύুāĻļীāϞāύী 5.2 ā§° āĻŽুāĻ্āϝ āϧাā§°āĻŖাāϏāĻŽূāĻš (Key Concepts & Formulas):
-
n-āϤāĻŽ āĻĒāĻĻā§° āϏূāϤ্ā§° (Formula for General/nth Term): āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিā§° n-āϤāĻŽ āĻĒāĻĻ āύিā§°্āĻŖāϝ়ā§° āĻŽূāϞ āϏূāϤ্ā§°āĻো āĻš'āϞ:
an = a + (n - 1)d
āϝ'āϤ, a = āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ, d = āϏাāϧাā§°āĻŖ āĻ āύ্āϤ⧰, n = āĻĒāĻĻā§° āϏংāĻ্āϝা, āĻā§°ু an = n-āϤāĻŽ āĻĒāĻĻ। - āĻĒāĻĻā§° āϏংāĻ্āϝা (Value of n): āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāϤ āĻĒāĻĻā§° āϏংāĻ্āϝা 'n' āϏāĻĻাāϝ় āĻāĻা āϧāύাāϤ্āĻŽāĻ āĻ āĻāĻŖ্āĻĄ āϏংāĻ্āϝা (Positive Integer) āĻš'āĻŦ āϞাāĻে। n ā§° āĻŽাāύ āĻেāϤিāϝ়াāĻ āĻāĻŖাāϤ্āĻŽāĻ āĻŦা āĻāĻ্āύাংāĻļ āĻš'āĻŦ āύোā§ąাā§°ে।
- āĻļেāώ⧰ āĻĢাāϞ⧰ āĻĒā§°া n-āϤāĻŽ āĻĒāĻĻ: āĻļেāώ⧰ āĻĢাāϞ⧰ āĻĒā§°া n-āϤāĻŽ āĻĒāĻĻ āύিā§°্āĻŖāϝ় āĻā§°িāĻŦāϞৈ āϏāĻŽাāύ্āϤ⧰ āĻĒ্ā§°āĻāϤিāĻো āĻāϞোāĻাāĻৈ āϞিāĻি āĻĒ্ā§°āĻĨāĻŽ āĻĒāĻĻ a = āĻļেāώ āĻĒāĻĻ (l) āĻā§°ু āϏাāϧাā§°āĻŖ āĻ āύ্āϤ⧰ -d āϞৈ āϏāĻŽাāϧাāύ āĻā§°া āĻšāϝ়।
❓ āĻĒ্ā§°াāϝ়েāĻ āϏোāϧা āĻĒ্ā§°āĻļ্āύāϏāĻŽূāĻš (Frequently Asked Questions - FAQs)
Q1. Class 10 maths 5.2 assamese medium question answer āĻŦোā§°āϤ āĻোāύো āĻāĻা āϏংāĻ্āϝা AP ā§° āĻĒāĻĻ āĻšāϝ়āύে āύāĻšāϝ় āĻেāύেāĻৈ āĻĒā§°ীāĻ্āώা āĻā§°া āĻšāϝ়?
Ans: āϏংāĻ্āϝাāĻোāĻ an āĻŦুāϞি āϧ⧰ি āϏূāϤ্ā§° an = a + (n - 1)d ā§° āĻĒā§°া n ā§° āĻŽাāύ āĻāϞিāĻā§ąা āĻšāϝ়। āϝāĻĻি n ā§° āĻŽাāύ āĻāĻা āϧāĻŖাāϤ্āĻŽāĻ āĻ āĻāĻŖ্āĻĄ āϏংāĻ্āϝা āĻšāϝ়, āϤেāύ্āϤে āϏংāĻ্āϝাāĻো AP āĻোā§° āĻĒāĻĻ āĻš'āĻŦ, āύāĻš'āϞে āύāĻšāϝ়।
Q2. Class 10 5.2 assamese new math solution pdf download āĻিāĻĻā§°ে āĻā§°িāĻŦ āĻĒাā§°ি?
Ans: āĻāĻĒুāύি āĻāĻŽাā§° āĻāĻ ā§ąেāĻŦāĻাāĻāĻā§° āĻĒā§°াāĻ Class 10 Chapter 5 Exercise 5.2 ā§° āϏāĻŽ্āĻĒূā§°্āĻŖ āϏāĻŽাāϧাāύ āĻŽোāĻŦাāĻāϞ āĻŦা āĻāĻŽ্āĻĒিāĻāĻাā§°āϤ āϏāĻšাāĻে āĻĒāĻĸ়িāĻŦ āĻā§°ু āĻĒ্ā§°āϝ়োāĻāύে āϏংā§°āĻ্āώāĻŖ āĻā§°ি ā§°াāĻিāĻŦ āĻĒাā§°িāĻŦ।
Q3. āĻ āύুāĻļীāϞāύী 5.2 class 10 ā§° āĻĒā§°া SEBA āĻŽেāĻ্ā§°িāĻ āĻĒā§°ীāĻ্āώাāϤ āĻি āϧ⧰āĻŖā§° āĻĒ্ā§°āĻļ্āύ āĻāĻšে?
Ans: āϏাāϧাā§°āĻŖāϤে āύিā§°্āĻĻিāώ্āĻ āĻĒāĻĻ āύিā§°্āĻŖāϝ় āĻā§°া (āϝেāύে: 30āϤāĻŽ āĻĒāĻĻ), āϞুāĻĒ্āϤ āĻĒāĻĻ āύিā§°্āĻŖāϝ়, āĻŦিāĻাāĻ্āϝ āϏংāĻ্āϝাā§° āϏংāĻ্āϝা āĻāϞিāĻā§ąা (āϝেāύে: 7 ā§°ে āĻŦিāĻাāĻ্āϝ 3 āĻ ংāĻā§° āϏংāĻ্āϝা) āĻā§°ু āĻā§°্āϤāĻিāϤ্āϤিāĻ 2 ā§° āĻĒā§°া 4 āύāĻŽ্āĻŦā§°ā§° āĻĒ্ā§°āĻļ্āύ āϏোāϧা āĻšāϝ়।
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