\(x^2-16y^2-6x+9\)
\(=x^2-6x+9-\left(4y\right)^2\)
\(=\left(x-3\right)^2-\left(4y\right)^2\)
\(=\left(x-3-4y\right)\left(x-3+4y\right)\)
\(x^3+20-4x-5x^2\)
\(=x^2\left(x-5\right)-4\left(x-5\right)\)
\(=\left(x-5\right)\cdot\left(x^2-4\right)\)
\(=\left(x-5\right)\cdot\left(x+2\right)\cdot\left(x-2\right)\)
\(x^2-3x+2\)
\(=x^2-x-2x+2\)
\(=x\cdot\left(x-1\right)-2\left(x-1\right)\)
\(=\left(x-1\right)\cdot\left(x-2\right)\)
a) Ta có: \(x^2-6x+9-16y^2\)
\(=\left(x-3\right)^2-\left(4y\right)^2\)
=(x-4y-3)(x+4y-3)
b) Ta có: \(x^3+20-5x^2-4x\)
\(=x^2\left(x-5\right)-4\left(x-5\right)\)
\(=\left(x-5\right)\left(x-2\right)\left(x+2\right)\)
c) Ta có: \(x^3-3x+2\)
\(=x^3-x-2x+2\)
\(=x\left(x-1\right)\left(x+1\right)-2\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+x-2\right)\)
\(=\left(x-1\right)^2\cdot\left(x+2\right)\)
