Question

81 -y^4

Answer 1

\(81-y^4=\left(9-y^2\right)\left(9+y^2\right)=\left(3-y\right)\left(y+3\right)\left(y^2+9\right)\)

Answer 2

\(81-y^4=\left(9-y^2\right)\left(9+y^2\right)=\left(3-y\right)\left(3+y\right)\left(9+y^2\right)\)