\(x^6-x^4-9x^3+9x^2\)
\(=x^4\left(x^2-1\right)-9x^2\left(x-1\right)\)
\(=x^4\left(x+1\right)\left(x-1\right)-9x^2\left(x-1\right)\)
\(=\left(x^5+x^4\right)\left(x-1\right)-9x^2\left(x-1\right)\)
\(=\left(x-1\right)\left(x^5+x^4-9x^2\right)\)
\(x^4+x^3+6x^2+5x+5\)
\(=x^4+x^3+x^2+5x^2+5x+5\)
\(=x^2\left(x^2+x+1\right)+5\left(x^2+x+1\right)\)
\(=\left(x^2+5\right)\left(x^2+x+1\right)\)
\(\left(12x^2-12xy+3y^2\right)-10\left(2x-y\right)+8\)
\(=3\left(4x^2-4xy+y^2\right)-10\left(2x-y\right)+8\)
\(=3\left[\left(2x\right)^2-2.2x.y+y^2\right]-10\left(2x-y\right)+8\)
\(=3\left(2x-y\right)^2-10\left(2x-y\right)+8\)
\(=\left(2x-y\right)\left[3\left(2x-y\right)-10\right]+8\)
\(=\left(2x-y\right)\left(6x-3y-10\right)+8\)
