[1/x-y)-1/(x+y)）÷2y/(x平方+2xy+y平方)
=(x+y-x+y)/(x-y)(x+y)÷2y/(x+y)²
=(x+y)/(x-y) x=根号3+2,y=根号3
=(√3+2+√3)/(√3+2-√3)
=(2√3+2)/2
=√3+1