I know that:

$\displaystyle (7^{x+2}(-9)^{x+2}) = (-63)^{x+2}$

My brain appears to be shutting down as to the reason why, I think the rule is:

$\displaystyle x^m y^m = xy^m $

but this one is not in the textbook. If this is right any chance someone could explain why it is right (being a bit dizzy tonight).

Thanks in advance,

Alice