Question

Answer these question

Answer 1

I hope it will help you.....

Answer 2

Let a-3d, a-d, a+d, a+3d are in A.P.

Acc. to question

a - 3d + a- d + a+ d a+3d = 32

4a = 32

a = 8

[ (a- 3d )(a+3d) ] 15 = [ ( a-d ) ( a+d ) ] 7

$15(a { }^{2} - (3d)^{2}) = (a { }^{2} - d ^{2})7$

$15a ^{2} - 135d { }^{2} = 7a {}^{2} - 7d {}^{2}$

$15a {}^{2} - 7a {}^{2} = 135d {}^{2} - 7d {}^{2}$

$8(64) = 128d {}^{2}$

$d {}^{2} = 8 \times 64 \div 128$

$d {}^{2} = 4$

$d = 4$

A.P. = -4 , 4 , 12 ,20