Question

The sum of 5th and 9th terms of an A.P. is 30 .If its 25th term is three times its 8th term find the A.P.

Answer 1

HEYA!!!

Here is your answer :
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Given,

Sum of 5th term and 9th term = 30

a + 4d + a + 8d = 30

2a + 12d = 30 --------------(1)

Given,

25th term of AP is 3 times 8th term.

3 (a + 7d ) = a + 24d

3a + 21 d = a + 24d

2a - 3d = 0 ------------(2)

Solve (1) & (2)

2a + 12d = 30
2a - 3d. = 0
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15d = 30

d = 30/15
d = 2

Substitute 2 in eq - 1

2a + 12d = 30

2a+ 12 (2) = 30

2a +24 = 30

2a = 30 - 24

2a = 6

a = 6/2

a = 3

Therefore,

AP = 3, 5, 7..........


HOPE THIS HELPS U. . .