Question

Sum of the first sixth terms in geometric sequence 3, -6, 12, -24,..​

Answer 1

Answer:-

-63

Step-by-step explanation:

Given

3, -6, 12, -24,.... are in G.P

Here a₁ = a = 3

Common ration r = a₂/a₁ = -6/3 = -2

r = -2

We know that

Sum of 'n' terms in G.P with common ration 'r' = a(rⁿ - 1)/(r - 1)

Here a = 3, r = -2, n = 6

∴Sum of the first 6 terms in G.P with a = 3 and r = -2

  = a(rⁿ - 1)/(r - 1)

  = 3((-2)⁶ - 1)/( -2 - 1)

  = 3(64 - 1) / (-3)

  = -(63)

∴Sum of the first 6 terms in the given G.P = -63