Đáp án:
a, `x^4 + 4`
`= (x^4 + 4x^2 + 4) - 4x^2`
`= (x^2 + 2)^2 - (2x)^2`
`= (x^2 - 2x + 2)(x^2 + 2x + 2)`
b, `x^4 + 64`
`= (x^4 + 16x^2 + 64) - 16x^2`
`= (x^2 + 8)^2 - (4x)^2`
`= (x^2 - 4x + 8)(x^2 + 4x + 8)`
c, `x^8 + x^7 + 1`
`= (x^8 + x^6 + x^7) - (x^6 - 1)`
`= x^6(x^2 + x + 1) - (x^3 - 1)(x^3 + 1)`
`= x^6(x^2 + x + 1) - (x - 1)(x^2 + x + 1)(x^3 + 1)`
`= (x^2 + x + 1)(x^6 - x^4 + x^3 - x + 1)`
d, `x^8 + x^4 + 1`
`= (x^8 + 2x^4 + 1) - x^4`
`= (x^4 + 1)^2 - (x^2)^2`
`= (x^4 - x^2 + 1)(x^4 + x^2 + 1)`
e, `x^5 + x + 1`
`= x^5 - x^2 + (x^2 + x + 1)`
`= x^2(x^3 - 1) + (x^2 + x + 1) `
`= x^2(x - 1)(x^2 + x + 1) + (x^2 + x + 1) `
`= (x^2 + x + 1)(x^3 - x^2 + 1)`
Giải thích các bước giải:
