To know this you first need to know the basic concept of sign multiplication:
If minus(-) sign is outside the power then it remains same if we multiply any number with this.
But if minus(-) sign is inside the power then it will be evaluated as:
if minus(-) to the power is even then minus will become (+)
that is (-)n = (+) if n is even and
if minus(-) to the power is odd then minus will remain same
that is (-)n = (-) if n is odd.
In your question -A2 minus sign is outside the power so the sign will remain same and if we put the value of A=3
Then, we will get -32 = -9
Hope you understand :)