Bài 3.
\(a,x^2-7xy+10y^2\)
\(=x^2-5xy-2xy+10y^2\)
\(=x\left(x-5y\right)-2y\left(x-5y\right)\)
\(=\left(x-5y\right)\left(x-2y\right)\)
\(b,5x^2+6xy+y^2\)
\(=5x^2+5xy+xy+y^2\)
\(=5x\left(x+y\right)+y\left(x+y\right)\)
\(=\left(x+y\right)\left(5x+y\right)\)
\(c,x^4-2x^3+2x-1\)
\(=\left(x^4-1\right)-\left(2x^3-2x\right)\)
\(=\left(x^2-1\right)\left(x^2+1\right)-2x\left(x^2-1\right)\)
\(=\left(x^2-1\right)\left(x^2+1-2x\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(x^2-2x+1\right)\)
\(=\left(x-1\right)^2\left(x+1\right)\)
\(d,\) Giống phần c nhé!
\(e,x^3-2x^2-5x+6\)
\(=x^3+x^2-3x^2-3x-2x+6\)
\(=\left(x^3+x^2-2x\right)-\left(3x^2+3x-6\right)\)
\(=x\left(x^2+x-2\right)-3\left(x^2+x-2\right)\)
\(=\left(x-3\right)\left(x^2+x-2\right)\)
\(=\left(x-3\right)\left(x^2+2x-x-2\right)\)
\(=\left(x-3\right)\left[x\left(x+2\right)-\left(x+2\right)\right]\)
\(=\left(x-3\right)\left(x+2\right)\left(x-1\right)\)