Question

brainlies plz answer

Answer 1

Let the GP be a,ar,ar^2.

Given that sum of first three terms = 14.

a + ar + ar^2 = 14

Given that sum of next three terms = 112

ar^3 + ar^4 + ar^5 = 112.


On Dividing (1) & (2), we get

r^3 = 112/14

r^3 = 8

r = 2.


Substitute r = 2 in (1), we get

a + ar + ar^2 = 14

a + 2a + 4a = 14

a = 14/7

a = 2.


Now,

Sum of n terms = a(r^n - 1)/r - 1

                           = 2(2^n - 1)/2 - 1

                           = 2(2^n - 1).


Hope this helps!