\(x^2-9x+8\)
\(=x^2-8x-x+8\)
\(=x.\left(x-8\right)-\left(x-8\right)\)
\(=\left(x-8\right).\left(x-1\right)\)
\(x^2+6x+8\)
\(=x^2+4x+2x+8\)
\(=x.\left(x+4\right)+2.\left(x+4\right)\)
\(=\left(x+2\right).\left(x+4\right)\)
P/S: mk chỉ bt làm 2 bài này thôi =)
a) \(2x^2-4xy+2y^2-32\)
\(=2\left(x^2-2xy+y^2-16\right)\)
\(=2\left[\left(x-y\right)^2-4^2\right]\)
\(=2\left(x-y-4\right)\left(x-y+4\right)\)
b) \(5x^2-5y^2-x+y\)
\(=5\left(x^2-y^2\right)-\left(x-y\right)\)
\(=5\left(x-y\right)\left(x+y\right)-\left(x-y\right)\)
\(=\left(x-y\right)\left[5\left(x+y\right)-1\right]\)
\(=\left(x-y\right)\left(5x+5y-1\right)\)
c) \(x^2-9x+8\)
\(=x^2-x-8x+8\)
\(=x\left(x-1\right)-8\left(x-1\right)\)
\(=\left(x-1\right)\left(x-8\right)\)
d) \(x^2+6x+8\)
\(=x^2+2x+4x+8\)
\(=x\left(x+2\right)+4\left(x+2\right)\)
\(=\left(x+2\right)\left(x+4\right)\)
