已知m等于三分之一,n等于二十七分之一,求 根号m减根号n分之m减n加根号m减2根号n分之

m=1/3
n=1/27
(m-n)/(√m-√n)+(m+4n-√nmn)/(√m-2√n)
=(√m-√n)(√m+√n)/(√m-√n)+(√m-2√n)^2/(√m-2√n)
=(√m+√n)+(√m-2√n)
=√m+√n+√m-2√n
=2√m-√n
=2*√(1/3)-√(1/27)
=2√3/3-√(1/3)/3
=2√3/3-√3/9
=6√3/9-√3/9
=5√3/9