Câu a : \(x^2+5x-6\)
\(=x^2-x+6x-6\)
\(=x\left(x-1\right)+6\left(x-1\right)\)
\(=\left(x-1\right)\left(x+6\right)\)
Câu b : \(5x^2+5xy-x-y\)
\(=5x\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(5x-1\right)\)
Câu c : \(7x-6x^2-2\)
\(=-6x^2+7x-2\)
\(=-6x^2+3x+4x-2\)
\(=-3x\left(2x-1\right)+2\left(2x-1\right)\)
\(=\left(2x-1\right)\left(2-3x\right)\)