a: \(=2x^3+x^2-2x^2-x+6x+3\)
\(=\left(2x+1\right)\left(x^2-x+3\right)\)
b: \(=x^3+x^2+4x^2+4x+4x+4\)
\(=\left(x+1\right)\left(x^2+4x+4\right)\)
\(=\left(x+1\right)\left(x+2\right)^2\)
c: \(=\left(x^2+7x+12\right)\left(x^2+7x+10\right)-24\)
\(=\left(x^2+7x\right)^2+22\left(x^2+7x\right)+96\)
\(=\left(x^2+7x+6\right)\left(x^2+7x+16\right)\)
\(=\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)\)