Answer
$$(x - 2)(y + 4)$$
Work Step by Step
To factor by grouping, you choose two terms and see what the greatest common factor is for those two terms and you factor it out. First, select which terms you will group together:
$$(xy + 4x) + (-2y - 8)$$
For the first grouping, we see that the greatest common factor is $x$, and for the second grouping, we see that the greatest common factor is $-2$, so we factor these out:
$$x(y + 4) - 2(y + 4)$$
We see that we can factor out an $y + 4$ from both terms to get:
$$(x - 2)(y + 4)$$
