Question

-y(3x - y)²=?????????????? ​

Answer 1

$-y\cdot\Big(3x-y\Big)^2 = -y\cdot\Big((3x)^2-2\cdot3x\cdot y+(y)^2\Big)=\\\\-y\cdot\Big(9x^2-6xy+y^2\Big)=-9x^2y+6xy^2-y^3$