Answer
$(x+1)(4x-5)$
Work Step by Step
$4x^{2}-x-5=$
Two factors of $ac=-20$, whose sum is $b=-1$
are $4$ and $-5$.
Rewrite $x$ as $4x-5x$ and factor in pairs.
$4x^{2}-x-5$
$=4x^{2}+4x-5x-5\qquad$...factor from each group.
$=4x(x+1)-5(x+1)\qquad$...factor out the common binomial factor,$x+1$.
$=(x+1)(4x-5)$
