\(x^3-x^2-14x+24\)
\(=x^3-3x^2+2x^2-6x-8x+24\)
\(=\left(x^3-3x^2\right)+\left(2x^2-6x\right)-\left(8x-24\right)\)
\(=x^2.\left(x-3\right)+2x.\left(x-3\right)-8.\left(x-3\right)\)
\(=\left(x-3\right).\left(x^2+2x-8\right)\)
\(=\left(x-3\right).\left(x^2+4x-2x-8\right)\)
\(=\left(x-3\right).\left[\left(x^2+4x\right)-\left(2x+8\right)\right]\)
\(=\left(x-3\right).\left[x.\left(x+4\right)-2.\left(x+4\right)\right]\)
\(=\left(x-3\right).\left(x+4\right).\left(x-2\right)\)
Chúc bạn học tốt!
tớ nghĩ \(x^3-x^2-14x+25\) thì mới hợp lí
