Question

The sum of the first two terms of a Geometric Progression is 36 and the product of the first and third terms is 9 times the second term. Find the sum of the first 8 terms.

Answer 1

Answer:

so given

a+ar=36 (say equation 1)

here r is the common ratio .

a×ar^2=9×ar

after simplifying above ar=9 , there fore second term of series is 9

substitute that value in equation 1 .then we get a= 27 then r= 1/3

we got all parameters to do sum

substitute in sum of n terms in GP I.e , Sn = a(1_r^n)/1_r (r is less than 1)