\(5x^2-8xy-4y^2\)
\(=\left(5x^2-10xy\right)+\left(2xy-4y^2\right)\)
\(=5x\left(x-2y\right)+2y\left(x-2y\right)\)
\(=\left(5x+2y\right)\left(x-2y\right)\)
Sử dụng phương pháp tách hạng tử :
\(5x^2-8xy-4y^2\)
\(=5x^2-10xy+2xy-4y^2\)
\(=5x\left(x-2\right)+2y\left(x-2\right)\)
\(=\left(5x+2y\right)\left(x-2\right)\)