ajutor!!!!!!! Punctul c va rog mult

Răspuns:
b2=b1×q
b4=b1×q³
b4/b2=b1×q³/b1×q=q²=128/8=16=> q=+_ 4
1. q=4
b2=8=4×b1=> b1=2
b3=b2×q=4×8=32
2.q=-4
b2=8=(-4)×b1=> b1=-2
b3=b2×q=-4×8=-32