`***` Lời giải chi tiết `***`
`(5x-2)(x+1)-3x(x^{2}-x-3)-2x(x-5)(x+4)+5x(x^{2}-7)`
`=5x^{2}-2x+5x-2-3x^{3}+3x^{2}+9x-2x(x^{2}-5x+4x-20)+5x^{3}-35x`
`=5x^{2}-2x+5x-2-3x^{3}+3x^{2}+9x-2x(x^{2}-x-20)+5x^{3}-35x`
`=5x^{2}-2x+5x-2-3x^{3}+3x^{2}+9x-2x^{3}+2x^{2}+40x+5x^{3}-35x`
`=(-3x^{3}-2x^{3}+5x^{3})+(5x^{2}+3x^{2}+2x^{2})+(-2x+5x+9x+40x-35x)-2`
`=10x^{2}+17x-2`