## Elementary Technical Mathematics

$(a-3)(a+8)$
We need to factor: $a^2+5a-24$ The first term in each binomial must be $a$, since $a^2$ has no coefficient. The operation in each binomial must be one subtraction and one addition since the second term in the trinomial is positive and the third term is negative. Since $-3+8=5$ and $(-3)(8)=-24$, the other two terms are $-3$ and $8$. Thus, we have: $a^2+5a-24=(a-3)(a+8)$