f(x)=[(1-X²)^½]/X 在区间(0,1)任取X1,X2且X1f(x1)=[(1-X1²)^½]/X1,f(x2)=[(1-X2²)^½]/X2 f(x1)-f(x2)=[(1-X1²)^½]/X1-[(1-X2²)^½]/X2 ={[(1-X1²)^½]*X2-[(1-X2²)^½]*X1}/X1X2 {[(1-X1²)^½]*X2-[(1-X2²)^½]*X1}>0 X1X2>0f(x1)-f(x2)>0 , f(x1)>f(x2)所以:f(x)在区间(0,1)上是减函数