Question

What is the sum of the first 6 terms of the series
-1+4-16+...

Answer 1

819

Explanation:

Givens

• a = -1
• r = - 4
• n = 6

Formula

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

Sum = -1(1 - (-4)^6 / (1 - -4)

Sum = -1 (1 - 4096) / 5

Sum = -1 (- 4095 ) / 5

Sum = 819