How do you factor 200x2+800x+800?

1 Answer
May 12, 2016

200x2+800x+800=200(x+2)2

Explanation:

All of the terms are divisible by 200, so separate that out first:

200x2+800x+800=200(x2+4x+4)

The remaining quadratic factor is a perfect square trinomial:

x2+4x+4=(x+2)2

Look at the pattern of the coefficients. It might remind you of this:

144=122

This is no coincidence. The coefficients are all small enough that no digits are carried during the multiplication of 12×12, so the digits 1,4,4 of 144 are the coefficients you get when you square (x+2).

Putting it all together:

200x2+800x+800=200(x+2)2