∵y=[1-√(1+4x)]/[1+√(1+4x)]
==>y+1=2/[1+√(1+4x)]
==>1+√(1+4x)=2/(y+1)
==>√(1+4x)=2/(y+1)-1
==>√(1+4x)=(1-y)/(y+1)
==>(1+4x)=(1-y)²/(y+1)²
==>4x=(1-y)²/(y+1)²-1
==>4x=-4y/(y+1)²
==>x=-y/(y+1)²
∴y=[1-√(1+4x)]/[1+√(1+4x)]的反函数是：y=-x/(x+1)².
大学数学求反函数y=（1-根号下（1+4x））/（1+根号下(1+4x)）的反函数