+117 What is the sum of the first five terms of the geometric series 1 − 3 + 9 − . . . ?
Hint: r ≠ 1, where a1 is the first term and r is the common ratio.
S5 = −182
S5 = −20
S5 = 61
S5 = 75
I know it's not B...I don't even know where to start. Help?
