\(\left(x-3\right)\left(x-10\right)\left(x-5\right)\left(x-6\right)-24x^2\)
\(=\left(x^2+30-13x\right)\left(x^2+30-11x\right)-24x^2\)
\(=\left(x^2+30x-12x-x\right)\left(x^2+30x-12x+x\right)-24x^2\)
\(=\left(x^2+30-12x\right)^2-x^2-24x^2\)
\(=\left(x^2-12x+30\right)^2-\left(5x\right)^2\)
\(=\left(x^2-12x+30+5x\right)\left(x^2-12x+30-5x\right)\)
\(=\left(x^2-7x+30\right)\left(x^2-17x+30\right)\)