How do you factor by grouping 2x^3 + 4x^2 y - 2x^2 - 4xy?

1 Answer
May 4, 2015

Notice the similarity of the coefficients, 2, 4, -2, -4. It prompts to group the four terms of this expression into two groups:
Group 1: 2x^3+4x^2y
Group 2: -2x^2-4xy

Factor out 2x^2 in the first group, getting
2x^2(x+2y)
Factor out -2x in the second group, getting
-2x(x+2y)

Now you see that (x+2y) is a common factor in both groups. Therefore, the original expression can be represented as:
2x^2(x+2y)-2x(x+2y)=(2x^2-2x)(x+y)=2x(x-1)(x+2y)