Answer
$7xy^2(-x^3+2y+3y^2)$
Work Step by Step
The greatest common factor of the coefficients -7, 14, and 21 is $7$.
The greatest common factor of $x^4, x,$ and $x$ is $x$.
The greatest common factor of $y^2, y^3,$ and $y^4$ is $y^23$
Thus, the greatest common factor of the three terms is $7xy^2$.
Factor out $7xy^2$ to obtain:
$=7xy^2(-x^3+2y+3y^2)$