Answer
$$2(x + 7)(x - 3)$$
Work Step by Step
Let us factor out the common factor of $2$:
$$2(x^2 + 4x - 21)$$
We need to factor the trinomial. We want to find which combination of factors for $21$ when added together will equal the middle coefficient of $4$.
Let us examine the factors for $-21$:
$-21$ and $1$ or $21$ and $-1$
$-7$ and $3$ or $7$ and $-3$
It looks like $7$ and $-3$ will work:
$$2(x + 7)(x - 3)$$