Đáp án + giải thích các bước giải:
m) `x^2+5x+6`
`=x^2+2x+3x+6`
`=x(x+2)+3(x+2)`
`=(x+3)(x+2)`
q) `(x+2)^3+(x-5)^3-(2x-3)^3`
`=(x+2+x-5)[(x+2)^2-(x+2)(x-5)+(x-5)^2]-(2x-3)^3`
`=(2x-3)(x^2+4x+4-(x^2+2x-5x-10)+x^2-10x+25)-(2x-3)^3`
`=(2x-3)[x^2+4x+4-x^2+3x+10+x^2-10x+25-(2x-3)^2]`
`=(2x-3)[x^2-3x+39-(4x^2-12x+9)]`
`=(2x-3)(x^2-3x+39-4x^2+12x-9)`
`=(2x-3)(-3x^2+9x+30)`
`=-3(2x-3)(x^2-3x-10)`
`=-3(2x-3)(x^2-5x+2x-10)`
`=-3(2x-3)[x(x-5)+2(x-5)]`
`=-3(2x-3)(x+2)(x-5)`