How do you factor $z^2+15z+36$ ?

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Answer 1 · 2017-01-03T21:42:19

Find two numbers that multiply to $36$ and add to $15$ , then expand it using the two numbers as coefficients of $z$ .

Of the factors of $36$ , $12$ and $3$ are the only two that add to $15$ .

$z^2+3z+12z+36$

$(z^2+3z)+(12z+36)$

$z(z+3)+12(z+3)$

$(z+3)(z+12)$

How do you factor z^2+15z+36z^2+15z+36?