Question

In a geometric progression, the sum of the 1st and 2nd terms is 12, and the sum of the 4th and 5th term is 324. find the sum of first 6 term in the series.

Answer 1

a+ax = 12

a(1+x) =12 => (1+x) = 12/a

and ax^3(1+x) = 324

ax^3 * 12/a = 324

x^3 = 27

x = 3

a = 3

so sum of first 6 terms =

3+9+27+81+243+729 = 1092

Answer 2

Step-by-step explanation:

(8x+1)(x+8)

=(8x+1)(x+8)

=(8x)(x)+(8x)(8)+(1)(x)+(1)(8)

=8x2+64x+x+8

=8x2+65x+8