x^2+()+y^2=()^2,x^2+()+9y^2=()^2

问题描述:

x^2+()+y^2=()^2,x^2+()+9y^2=()^2

x^2+(±2xy)+y^2=(x±y)^2,x^2+(±6xy)+9y^2=(x±3y)^2