Multiplying exponents with variables inside Why is 
$$(-1)^n(2^{n+2}) = (-2)^{n+2} ?$$
My thinking is that $-1^n \times 2^{n+2}$ should be $-2^{2n+2}$ but clearly this is not the case. Why is the variable essentially ignored, is there a special case of multiplication I'm unaware of?

This is due to the fact that $(-1)^{n+2}$ is the same thing as $(-1)^n$.  Hence, $(-1)^n2^{n+2}=(-1)^{n+2}2^{n+2}$, and by the properties of exponents, this is equal to $(-2)^{n+2}$.
