If `x= 28^(1/3) and y= 27^(1/3)` find the value of `x+y-1/(x^2+x y+y^2)`

Explanation

`x+y−1/(x^2+xy+y^2)`
`=((x-y)(x^2+xy+y^2)-1)/(x^2+xy+y^2)`
`=(x^3−y^3-1)/(x^2+xy+y^2)` {Using the identity `a^3-b^3=(a-b)(a^2+b^2+ab)`}
`=(((28)^(1/3))^3-((27)^(1/3))^3-1)/(x^2+xy+y^2)`
`=(28-27-1)/(x^2+xy+y^2)`
`=0/(x^2+xy+y^2)=0`