Ta có:

`C=x^5+y^5`

`=(x+y)^5-5x^4 y-10x^3 y^2 -10x^2 y^3 - 5xy^4 `

`=(x+y)^5-5xy(x^3+y^3)-10x^2 y^2(x+y)`

`=(x+y)^5-5xy[(x+y)^3-3xy(x+y)]-10(xy)^2 (x+y)`

`=3^5 - 5*(-10)*[3^3-3*(-10)*3]-10*(-10)^2 * 3`

`=243+50*117-3000`

`=3093`