√(1/5)=√5/5
√(2/3)-√(3/2)=√6/3-√6/2=-√6/6
√18-√8+√(1/8)=3√2-2√2+√2/4=5√2/4
√(25/2)+√99-√18=5√2/2+3√11-3√2=3√11-√2/2