Question

2, -8, 32, -128, 512

Answer 1

hi!

Answer 2

think about this for a second:
2^1=2
2^2=4
2^3=8
2^4=16
2^5=32
2^6=64
2^7=128

look at when the power is odd
what do you notice about your sequence of numbers ?

Answer 3

then also consider that your sequence alternates