how to solve it? 關於 開方根

[rt(x)+x]/[1+x+rt(x)] = [rt(x)+x]/[1+x+rt(x)]* [1+x-rt(x)]/[1+x-rt(x)]
=[rt(x)+x][1+x-rt(x)] / [(1+x)^2 -(rt(x))^2]
=rt(x)+xrt(x)-x+x+x^2-xrt(x) / (1+x+x^2)
=[x^2+rt(x)]/(1+x+x^2)