Answer
$(x-7)(x+4)$
Work Step by Step
We need to factor:
$x^2 - 3x -28$
The first term in each binomial must be $x$, since $x^2$ has no coefficient.
The operation in each binomial must be subtraction and addition since the second term in the trinomial is negative and the third term is negative.
Since $-7+4=-3$ and $(-7)(4)=-28$, the other two terms are $-7$ and $4$.
Thus, we have:
$x^2 - 3x -28
=(x-7)(x+4)$
