\(P\left(x\right)=6x^3+13x^2+4x-3\)
\(=\left(6x^3+6x^2\right)+\left(7x^2+7x\right)-\left(3x-3\right)\)
\(=6x^2\left(x+1\right)+7x\left(x+1\right)-3\left(x+1\right)\)
\(=\left(6x^2+7x-3\right)\left(x+1\right)\)
\(=\left[\left(6x^2-2x\right)+\left(9x-3\right)\right]\left(x+1\right)\)
\(=\left[2x\left(3x-1\right)+3\left(3x-1\right)\right]\left(x+1\right)\)
\(=\left(3x-1\right)\left(2x+3\right)\left(x+1\right)\)