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Show that f (x) = 2x + cot-1 x + log [√(1 + x2) – x] is increasing in R.

Given,

 

   

differentiating the two sides w.r.t. x, we get

On figuring out both the sides, we get

 

   

   

   

   

The above is valid for any worth of x ∈ R.

 

In this manner, the given capacity is an expanding capacity over R.