Question

question
factor.
$x^2 + 13x + 36$

Explanation:

Step1: Find pair summing to 13, product 36

The pair is 4 and 9, since $4+9=13$ and $4\times9=36$.

Step2: Split middle term and factor

Rewrite the trinomial as $x^2 + 4x + 9x + 36$, then group:
$(x^2 + 4x) + (9x + 36) = x(x+4) + 9(x+4)$
Factor out $(x+4)$: $(x+4)(x+9)$

Answer:

$(x+4)(x+9)$