Answer
$-2(h-7)(h+5)$
Work Step by Step
$-2h^{2}+4h+70=$
...factor out the GCF.
$=-2(h^{2}-2h-35)$
...find factors of $ac$ with a sum of $b$.
($ac=-35,\ b=-2$)
$\left[\begin{array}{lll}
\text{Factors of -35} & \text{Sum of factors} & \\
1\text{ and }-35 & -34 & \\
-1\text{ and }35 & 34 & \\
5\text{ and }-7 & -2 & \text{ is what we need }
\end{array}\right]$
...use the factors you found to rewrite $bx$.
$=-2(h^{2}+5h-7h-35)$
...factor by grouping.
$=-2[h(h+5)-7(h+5)]$
...factor again.
$=-2(h-7)(h+5)$
