G(x)=sqrt(x), then

f'(x)= 1/x，

g'(x)= 1/[2sqrt(x)]，

According to Cauchy's differential mean value theorem, it is concluded that

[f(b)-f(a)]/[sqrt(b)-sqrt(a)]= f '(c)/g '(c)= 2/sqrt(c)& lt；

[sqrt(b)+sqrt(a)]/sqrt(ab), where a