Đáp án `+`Giải thích các bước giải:
` C1:`
` x^3 - 7x - 6 `
` = x^3 + 3x^2 + 2x - 3x^2 - 9x - 6`
` = (x^3 + 3x^2 + 2x) - (3x^2 + 9x + 6) `
` = x(x^2 + 3x + 2) - 3(x^2 + 3x + 2) `
` = (x^2 + 3x + 2 )(x - 3) `
` = (x^2 + x + 2x + 2)(x-3) `
` = [x(x + 1) + 2(x+1)](x-3)`
` = (x-3)(x+1)(x+2)`
` C2:`
`x^3 - 7x - 6`
`= x^3 - 7x + 1 - 7`
` = (x^3 + 1) - (7x + 7) `
` =(x + 1)(x^2 - x + 1) - 7(x+1)`
` = (x+1)(x^2 - x + 1 - 7) `
` = (x+1)(x^2 - x - 6) `
` = (x+1)(x^2 + 2x - 3x - 6)`
`= (x+1)[x(x + 2) -3(x+2)] `
`= (x + 1)(x + 2)( x - 3)`
