The 23rd term and 37th term of an AP are 54, 96 Find 30th term
Answers
EXPLANATION.
23rd term of an A.P. = 54.
37th term of an A.P. = 96.
As we know that,
General term of an A.P.
⇒ Tₙ = a + (n - 1)d.
⇒ T₂₃ = a + (23 - 1)d.
⇒ T₂₃ = a + 22d.
⇒ a + 22d = 54. ⇒ (1)
⇒ T₃₇ = a + (37 - 1)d.
⇒ T₃₇ = a + 36d.
⇒ a + 36d = 96. ⇒ (2).
From equation (1) & (2), we get.
⇒ a + 22d = 54.
⇒ a + 36d = 96.
We get.
⇒ - 14d = - 42.
⇒ 14d = 42.
⇒ d = 42/14.
⇒ d = 3.
Put the value of d = 3 in equation (1), we get.
⇒ a + 22d = 54.
⇒ a + 22(3) = 54.
⇒ a + 66 = 54.
⇒ a = 54 - 66.
⇒ a = -12.
To find 30th term of an A.P.
⇒ T₃₀ = a + (30 - 1)d.
⇒ T₃₀ = a + 29d.
⇒ T₃₀ = -12 + 29(3).
⇒ T₃₀ = -12 + 87.
⇒ T₃₀ = 75.
MORE INFORMATION.
Supposition of terms in A.P.
(1) = Three terms as : a - d, a, a + d.
(2) = Four terms as : a - 3d, a - d, a + d, a + 3d.
(3) = Five terms as : a - 2d, a - d, a, a + d, a + 2d.
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❦ANSWER彡
GIVEN :-
‣30th term = ?
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1) 23rd term
➣T(23) = a+(23-1) d = 54
➣T(23) = a+22d = 54
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2) 37th term
➣T(37) = a+ (37-1)d = 96
➣T(37) = a+36d = 96
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‣NOW HAVE TO FIND 30th TERM :-
First equation = T(23) = a+22d = 54
Second equation = T(37) = a+36d = 96
➣ a + 22d = 54
➣ a + 36d = 96
‣ -14d = -42
‣ d = 3
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NOW, PUT d = 3
➣ a + 22d = 54
➣a+22(3)= 54
➣a+66=54
➣a = -12
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30th TERM :-
‣T(30) = a+ (30-1) d
‣T(30) = -12+ (30-1) (3)
‣T(30) = -12+ (29) (3)
‣T(30) = -12 + 87
‣ T(30) = 75
SO, THE VALUE OF 30th TERM = 75
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