x³+y³=n(x+y)(x²-xy+y²)=n(x+y)[(x+y)²-3xy]=nx+y=m代入m(m²-3xy)=nm²-3xy=n/mxy=(m³- n)/(3m)x²+y²=(x+y)²-2xy=m²-2(m³-n)/(3m)=(3m³-2m³+2n)/(3m)=(m³+2n)/(3m)=m²/3 +2n/(3m)
