2y(3x + 1)
(3x + 3y)(x + y) = 3(x + y)2
(3x + 3y)(x + y) or 3(x + y)2
(3x - y)(3x - y) - 81
(-3x - 1)(3x - 7)
(3x - y)(3x - y)
2y(3x + 1)
3x
(3x + 3y)(x + y) = 3(x + y)2
9x^2-6xy+y^2 = (y-3x)^2 (y-3x)^2-81 -> ((y-3x)+9)((y-3x)-9)
(3x + 3y)(x + y) or 3(x + y)2
9x2 - 6xy + y2 - 81 = (3x - y)2 - 81 = (3x - y - 9)*(3x - y + 9)
The GCF is 3xy.
(3x - y)(3x - y) - 81
(3x - y + 9)(3x - y - 9)
9x2 - 6xy + y2 - 81 = (3x - y)2 - 81 (since the first three terms make a perfect square = (3x - y - 9)(3x - y + 9) since the expression now is a difference of two squares.
3x2+6xy+3y2= 3(x2+2xy+y2)= 3(x+y)2