Question

设f(根号下x)=1/X+2根号下x.求f(x)的表达示.解不等式f(x)

Answer 1

f(√x)=1/x +2√x let √x =t => x=t^2 ;x≠0 =>t≠0

=>f(t)=1/(t^2) +2t

=>再变换变数 f(x)= 1/(x^2) +2x ;x≠0