Question

-y(3x - y)²=?????????????? ​

Answer 1

$-ycdotBig(3x-yBig)^2 = -ycdotBig((3x)^2-2cdot3xcdot y+(y)^2Big)=\\-ycdotBig(9x^2-6xy+y^2Big)=-9x^2y+6xy^2-y^3$