Question

Find the 25th term of the an ap in which the third term is 7 and 7th term is 2 more than thrice the third term

Answer 1

3rd term=a+2d------equation(1)

7th term =a+6d

a+6d=2+3(3rd term)

a+6d=2+3(7)---(from equation 1)

a+6d=23-----equ2

sub equation (1) and(2), we get

4d=16

d=4

putting value of d in equation (1)

a+2d=7

a+2(4)=7

a=-1

25th term =a+24d

-1+24(4)

-1+96

95 answer