a, \(xy+2x+2y+y^2\)
\(=\left(xy+2x\right)+\left(y^2+2y\right)\)
\(=x.\left(y+2\right)+y.\left(y+2\right)\)
\(=\left(y+2\right).\left(x+y\right)\)
b, Sửa đề:
\(-6x^2-9xy+15y^2\)
\(=-\left(6x^2+9xy-15y^2\right)\)
\(=-\left(6x^2-6xy+15xy-15y^2\right)\)
\(=-\left[\left(6x^2-6xy\right)+\left(15xy-15y^2\right)\right]\)
\(=-\left[6x.\left(x-y\right)+15y.\left(x-y\right)\right]\)
\(=-\left[\left(x-y\right).\left(6x+15y\right)\right]\)
c, \(2x\left(x-3\right)+y\left(x-3\right)+\left(3-x\right)\)
\(=2x\left(x-3\right)+y\left(x-3\right)-\left(x-3\right)\)
\(=\left(x-3\right).\left(2x+y-1\right)\)
Chúc bạn học tốt!!!
