Answer
$(x-3)(x-4)$
Work Step by Step
We need to factor:
$x^2-7x+12$
The first term in each binomial must be $x$, since $x^2$ has no coefficient.
The operation in each binomial must be subtraction since the second term in the trinomial is negative and the third term is positive.
Since $-3-4=-7$ and $(-3)(-4)=12$, the other two terms are $-3$ and $-4$.
Thus, we have:
$x^2-7x+12=(x-3)(x-4)$
