So I have to factor this quadratic:
$-x^2 + 4$
I've rewritten it as:
$-x^2 + 0x + 4$
Then the factors that add to 0 and multiply to 4 are 2 and -2, so is the answer $-(x + 2)(x - 2)$ or $-(x - 2)(x + 2)$
Also, another question I have is the answer was written by the professor as:
$(2 - x)(2 + x)$
Which I just don't understand. Is that just another way of writing one of the above factorizations?