Q.
Let f:(0,∞)→(0,π) be a function defined by f(x)=cot−1(lnx) and g be the inverse function of f, then
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Continuity and Differentiability
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Solution:
f(1)=cot−1(0)=2π⇒g(2π)=1,f′(x)=x(1+ln2x)−1⇒f′(1)=−1
and f′′(x)=x2(1+ln2x)1+x2(1+ln2x)2lnx⇒f′′(1)=1 g′(2π)=f′(1)1=−1 g′′(2π)=(f′(1))3−(f′′(1))=−1−1=1