What is the first four terms of the geometric sequence where a1=−8 and r=−2 ?
(explanations appreciated!)

Answer:
-8, 16, -32, 64
Step-by-step explanation:
a1 = -8
r = -2
a2 = -8(-2)=16
a3 = -8(-2)²=-8(4)=-32
a4=-8(-2)³=-8(-8)=64