Question

Simplify: x^2-49

Answer 1

You want to use the reverse FOIL method to break up the equation. (front, outer, inner, last) When you do this, you can simplify the equation down to (x+8)*(x-7). That is equivalent to x^2+8x-7x-56 or x^2+x-56. 

Answer 2

For x^2-49
this is a diffarence of two perfect squares.  I suggest that this is memorised.
a^2-b^2=(a-b)(a+b)
so x^2-7^2=(x-7)(x+7)

so to solve x^2+x-56 you want to find out what two numbers add to 1 and multiply to make -56
since -56 is negative we know that the two number are difarent signs so that eliminatess answers B and D.
if we try answer C -8+7=-1 so the answer is not C because we want +1 not -1
then we see that 8+(-7)=1 so the answer is A