What is the sum of the first ten terms in the geometric series 4-12+36-108+ a.-59,048 b.-1,048,575 c.19,684 d.118,096

A. -59,048

The first pair of terms sums to -8; the second pair to -72. Each pair after that sums to a value 9 times the previous one. Then the sum of 10 terms is ...

... (-8) + (-72) + (-648) + (-5832) + (-52488)

Before you even add this up, you know the answer choice is A. The sum is ...

... -59, 048

Using the formula

The formula for the sum of a geometric series is ...

... S = a1·(r^n -1)/(r -1) . . . . . where a1 = 4 is the initial term, r=-3 is the common ratio, and n=10 is the number of terms.

Filling in the values and doing the arithmetic, we have ...

... S = 4·((-3)^10 -1)/(-3-1) = 4·(59,049 -1)/(-4) = -59,048