√(9+6r+r²-9)=2√3-√(4+4r+r²-4)
两边平方
6r+r²=12-4√[3(4r+r²)]+4r+r²
r-6=-2√(12r+3r²)]
两边平方
r²-12r+36=48r+12r²
11r²+60r-36=0
r=6/11,r=-6
√(9+6r+r²-9)=2√3-√(4+4r+r²-4)
两边平方
6r+r²=12-4√[3(4r+r²)]+4r+r²
r-6=-2√(12r+3r²)]
两边平方
r²-12r+36=48r+12r²
11r²+60r-36=0
r=6/11,r=-6