## Introductory Algebra for College Students (7th Edition)

$$2(x + 7)(x - 3)$$
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: $$2(x + 7)(x - 3)$$