Answer:
C; x = 4
Step-by-step explanation:
In these equations we can FOIL. That is, multiply the first numbers of both groups, the outside numbers, the inside numbers, and whatever is left last.
so x • x + x • -4 + -4 • x + -4 • -4 = 0
= x^2 + -4x + -4x + 16 = 0 (two negatives multiplied together always equal a positive number)
The X's can be added together, but not the X^2, since it has a different base.
So we get x^2 + -8x + 16 = 0 ( -4 + -4 = -8). We call this factored form.
In reality, we have two equations, x-4 and x-4, which are equal to zero. So x-4 =0 and x-4 =0. We can add 4 to both sides for the two equations, so x = 4 and x = 4. Since both solutions of x are the same, we only have one solution, x = 4.
You can honestly ignore the top paragraph if you want, I'm just a huge math nerd.
