Answer
$(x+6)(x+2)$
Work Step by Step
Use the hint.
Substituting $(x+1)=u$, the trinomial becomes
$u^{2}+6u+5=$
... Searching for two factors of $+5$ whose sum is $+6,$
we find$\qquad+5$ and $+1.$
= $(u+5)(u+1)$
... bring back x,
$=(x+1+5)(x+1+1)$
= $(x+6)(x+2)$