## Elementary Technical Mathematics

$3(r+5)^2$
Factor out the common term, 3, then factor the resulting trinomial. $3r^2+30r+75=3(r^2+10r+25)$ The first term in each binomial must be r, since $r^2$ has no coefficient. The operation in each binomial must be addition, since each term in the trinomial is positive. $5+5=10$ and $5\times5=25$, so the other two terms are 5 and 5. Since both binomials are $r+5$, they are written with an exponent of 2.