a) \(9x^2-4y^2\)
\(=\left(3x\right)^2-\left(2y\right)^2\)
\(=\left(3x-2y\right).\left(3x+2y\right)\)
b) \(2x.\left(x-y\right)-6y.\left(x-y\right)\)
\(=\left(x-y\right).\left(2x-6y\right)\)
\(=\left(x-y\right).2.\left(x-3y\right)\)
Chúc bạn học tốt!