x^3-x^2-20x (x^2+1)^2-(x+1)^2 6x^2-7x+2 x^4+8x^2+12

Đáp án`+`Giải thích các bước giải:

 ` x^3-x^2-20x `

` = x(x^2-x-20) `

` = x(x^2-5x+4x-20) `

` = x[x(x-5)+4(x-5)] `

` = x(x-5)(x+4) `

`-----------------`

 ` (x^2+1)^2-(x-1)^2 `

` = [(x^2+1)-(x-1)](x^2+1+x-1) `

` = (x^2+1-x+1)(x^2+x) `

` = x(x^2-x+2)(x+1) `

`-----------------`

 `6x^2-7x+2 `

` = 6x^2-3x-4x+2 `

` = 3x(2x-1)-2(2x-1) `

` = (3x-2)(2x-1) `

 `x^4+8x^2+12 `

` = x^4+2x^2+6x^2+12 `

` = x^2 (x^2+2)+6(x^2+2) `

` = (x^2+6)(x^2+2)`