\(a,8x^3+4x^2-y^3-y^2\)
\(=\left(8x^3-y^3\right)+\left(4x^2-y^2\right)\)
\(=\left[\left(2x\right)^3-y^3\right]+\left[\left(2x\right)^2-y^2\right]\)
\(=\left[\left(2x-y\right)\left(4x^2+2xy+y^2\right)\right]+\left[\left(2x-y\right)\left(2x+y\right)\right]\)
\(=\left(2x-y\right)\left(4x^2+2xy+y^2+2x+y\right)\)
\(b,x^2+5x-6\)
\(=x^2-x+6x-6\)
\(=x\left(x-1\right)+6\left(x-1\right)\)
\(=\left(x-1\right)\left(x+6\right)\)