Both signs in the trinomial are +, so both of our factors must have a +, and since we factored out the 2, our lead coefficient on the trinomial is 1, so that means the first term of each of our binomial factors is x. So far we have:
(x + _)(x + _)
The numbers that go into the two blanks have to be 4 when you multiply them together and 5 when you add them. Hmmm, 4 times 1 is 4 and 4 plus 1 is 5. Looks good, so:
(x + 1)(x + 4)
Now put the 2 back:
2(x + 1)(x + 4)
And you are done.
Check:
x times x is
1 times x is
x times 4 is
1 times 4 is
Add 'em up:
And put the 2 back in: Answer checks.
