1.
\(3x^2-3xy+5x-5y\)
\(=\left(3x^2-3xy\right)+\left(5x-5y\right)\)
\(=3x.\left(x-y\right)+5.\left(x-y\right)\)
\(=\left(x-y\right).\left(3x+5\right)\)
2.
\(x^2+y^2+2xy-x-y\)
\(=\left(x^2+2xy+y^2\right)-\left(x+y\right)\)
\(=\left(x+y\right)^2-\left(x+y\right)\)
\(=\left(x+y\right).\left(x+y-1\right)\)
3.
\(x^2-xy+x-y\)
\(=\left(x^2-xy\right)+\left(x-y\right)\)
\(=x.\left(x-y\right)+\left(x-y\right)\)
\(=\left(x-y\right).\left(x+1\right)\)
4.
\(x^2-2xy+y^2-z^2+2zt-t^2\)
\(=\left(x^2-2xy+y^2\right)-\left(z^2-2zt+t^2\right)\)
\(=\left(x-y\right)^2-\left(z-t\right)^2\)
\(=\left[x-y-\left(z-t\right)\right].\left[x-y+\left(z-t\right)\right]\)
\(=\left(x-y-z+t\right).\left(x-y+z-t\right)\)
6.
\(2x^2-8x+6\)
\(=2.\left(x^2-4x+3\right)\)
\(=2.\left(x^2-3x-x+3\right)\)
\(=2.\left[\left(x^2-3x\right)-\left(x-3\right)\right]\)
\(=2.\left[x.\left(x-3\right)-\left(x-3\right)\right]\)
\(=2.\left(x-3\right).\left(x-1\right)\)
Chúc bạn học tốt!