Cm đẳng thức: a, (x – y)(x^2 + xy +y^2) = x^3 – y^3 b, (x^3)(x^3 + 1) = (x^2)(x^2 + x + 1)(x^2 – x + 1) 23/08/2021 Bởi Josie Cm đẳng thức: a, (x – y)(x^2 + xy +y^2) = x^3 – y^3 b, (x^3)(x^3 + 1) = (x^2)(x^2 + x + 1)(x^2 – x + 1)
`a) (x – y)(x^2 + xy + y^2) = x^3 – y^3` `x^3 + x^2y + xy^2 – x^2y + xy^2 + y^3 = x^3 – y^3` `x^3 + 2xy^2 + y^3 = x^3 – y^3` `b) (x^3)(x^3 + 1) = (x^2)(x^2 + x + 1)(x^2 – x + 1)` `x^6 + x^3 = x^4 + x^3 + x^2` Bình luận
`a) (x – y)(x² + xy + y²) ` `= x³ + x²y + xy² – x²y – xy² – y³` `= x³ – y³` `b) x²(x² + x + 1)(x² – x + 1)` `= x²(“x^4` `- (x + 1)²)` `= x²[“x^4` `- (x² + 2x + 1)]` `= x²(“x^4` `- x² – 2x – 1)` `=` `x^6` – `x^4` – `2x^3` – x² Bình luận
`a) (x – y)(x^2 + xy + y^2) = x^3 – y^3`
`x^3 + x^2y + xy^2 – x^2y + xy^2 + y^3 = x^3 – y^3`
`x^3 + 2xy^2 + y^3 = x^3 – y^3`
`b) (x^3)(x^3 + 1) = (x^2)(x^2 + x + 1)(x^2 – x + 1)`
`x^6 + x^3 = x^4 + x^3 + x^2`
`a) (x – y)(x² + xy + y²) `
`= x³ + x²y + xy² – x²y – xy² – y³`
`= x³ – y³`
`b) x²(x² + x + 1)(x² – x + 1)`
`= x²(“x^4` `- (x + 1)²)`
`= x²[“x^4` `- (x² + 2x + 1)]`
`= x²(“x^4` `- x² – 2x – 1)`
`=` `x^6` – `x^4` – `2x^3` – x²