CAT4 #35 : If a and b are nonzero integers...

[NaomieO995]

If a and b are nonzero integers, which of the following must be negative?
(–a)^–2b
(–a)^–3b
–(a^–2b)
–(a^–3b)
None of these

The explanation says option B is positive. Can someone please explain how? all my calculation result say negative.

Thank you in advance.

[RonPurewal]

the second option doesn't HAVE TO be positive... but it CAN be positive.

specifically:
• if 'b' is even, that's enough to make the second option positive.
• if 'a' is negative, that's also enough to make the second option positive.