The Purplemath Forums

So, my problem is 2a^2 + 3a + 1. What I thought I had to do to factor this, would be to figure out what multiplies to equal 2 (2 * 1), and adds to 3. So, I figured it would be 2 and 1, making the answer (2a + 2)(a + 1). But when I checked it, this doesn't work. When I looked in the back of the book ...