Ta có; \(\left(x^2+x-6\right)\left(x^2+3x-4\right)-24\)
\(=\left(x+3\right)\left(x-2\right)\left(x+4\right)\left(x-1\right)-24\)
\(=\left(x+3\right)\left(x-1\right)\left(x+4\right)\left(x-2\right)-24\)
\(=\left(x^2+2x-3\right)\left(x^2+2x-8\right)-24\)
\(=\left(x^2+2x\right)^2-11\left(x^2+2x\right)+24-24\)
\(=\left(x^2+2x\right)^2-11\left(x^2+2x\right)\)
\(=\left(x^2+2x\right)\left(x^2+2x-11\right)\)
\(=x\left(x+2\right)\left(x^2+2x-11\right)\)