find the greatest common factor of 28y^4,20y^5,8y^2
[tex]28y^4=\boxed2\cdot\boxed2\cdot7\cdot\boxed{y}\cdot\boxed{y}\cdot y\cdot y\\\\20y^5=\boxed2\cdot\boxed2\cdot5\cdot\boxed{y}\cdot\boxed{y}\cdot y\cdot y\cdot y\\\\8y^2=\boxed2\cdot\boxed2\cdot2\cdot\boxed{y}\cdot\boxed{y}\\\\GCF(28y^4,\ 20y^,\ 8y^2)=\boxed2\cdot\boxed2\cdot\boxed{y}\cdot\boxed{y}=\boxed{\boxed{4y^2}}[/tex]