cho xyz khác 0 tm x^3y^3+y^3z^3+z^3×63=3x^2y^2z^2.Tính P=(1+x/y)(1+y/z)(1+z/x) 13/10/2021 Bởi Gabriella cho xyz khác 0 tm x^3y^3+y^3z^3+z^3×63=3x^2y^2z^2.Tính P=(1+x/y)(1+y/z)(1+z/x)
`3x²y²z² = x³y³+y³z³+z³x³+ (3x²y²z²)/(x³y³+y³z³+z³x³)` `= [(1+3x²y²z²) / (x³y³+y³z³+z³x³)] ` `= 1/3 +(x²y²z²)/(x³y³)+ (x²y²z²) / (y³z³) +(x²y²z²) / (z³x³)``= 1/3 +(z²)/(xy)+( x^2)/(yz)+ (y²)/(zx)` `= 1/3` Bình luận
`3x²y²z² = x³y³+y³z³+z³x³+ (3x²y²z²)/(x³y³+y³z³+z³x³)`
`= [(1+3x²y²z²) / (x³y³+y³z³+z³x³)] `
`= 1/3 +(x²y²z²)/(x³y³)+ (x²y²z²) / (y³z³) +(x²y²z²) / (z³x³)`
`= 1/3 +(z²)/(xy)+( x^2)/(yz)+ (y²)/(zx)`
`= 1/3`