Find the least value of `f(x)=a x+b/x ,` where `a >0,\ \ b >0` and `x >0` .

Explanation

Given `f(x)=a x+\frac{b}{x} \quad a>0, b>0, x>0`


`f(x)=a-\frac{b}{x^{2}}`



for critical points


`f^{\prime}(x)=0`
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