 factor in some trinomials. After looking at how to factor the difference of two squares, we may wonder what happens when instead of something like x plus 1 times x minus 1 we have x plus 1 times x plus 1. Let's see what happens here. We're multiplying these two terms but since we don't have that plus and minus term they're not going to, the middle terms are not going to cancel so we're just going to end up with x squared plus x plus x that is plus 2x plus 1 times 1, 1. So we have the square root of this term times and then the middle term is just times 2. And look at it here. It's just x plus 2 times x plus 2. This is x square plus 2x plus 2x right plus 2x plus 2x that's plus 4x plus 4. On here we have x plus 3 times x plus 3 which is x squared plus 3x plus 3x that is plus 6x plus 3 times 3 9. So what can we say about x squared plus 14x plus 49? Well the square root of 49 is 7 and 7 times 2 is 14 so this must factor as x plus 7 square. Now in general what can we infer? If we have a trinomial where the coefficient of the linear term is twice the square root of the constant then it will just factor as x plus a squared. Now usually this is not too helpful. People usually don't, some people do remember this formula but factoring is not about remembering formulas. It's more about understanding what's happening and with time you do remember some formulas but the emphasis should never be on memorizing formulas but an understanding whatever it is that we're doing.