1) \(x^2+4xy+4y^2-a^2+2ab-b^2\)
\(=\left(x+y\right)^2-\left(a-b\right)^2\)
\(=\left(x+y-a+b\right)\left(x+y+a-b\right)\)
4) \(ax^2+bx^2-6ax+6bx+9a+9b\)
\(=\left(ax^2-6ax+9a\right)+\left(bx^2+6bx+9b\right)\)
\(=a\left(x^2-6x+9\right)+b\left(x^2+6x+9\right)\)
\(=a\left(x-3\right)^2+b\left(x+3\right)^2\)
b) \(m^2-6m+9-x^2+4xy-4y^2\)
\(=\left(m-3\right)^2-\left(x-2y\right)^2\)
\(=\left(m-3-x+2y\right)\left(m-3+x-2y\right)\)
cho mình sửa lại câu 1 nghen
1) \(x^2+4xy+4y^2-a^2+2ab-b^2\)
\(=\left(x-2y\right)^2-\left(a-b\right)^2\)
\(=\left(x-2y-a+b\right)\left(x-2y+a-b\right)\)
5) \(8a^2xy-18b^2xy\)
\(=2xy\left(4a^2-9b^2\right)\)
\(=2xy\left(2a-3b\right)\left(2a+3b\right)\)