Elementary Technical Mathematics

$(x-3)(x-4)$
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: $x^2-7x+12=(x-3)(x-4)$