Let f : R $\to$ R be defined as $f(x) = {x^3} + x - 5$. If g(x) is a function such that $f(g(x)) = x,\forall 'x' \in R$, then g'(63) is equal to ________________.
Solution
<p>$f(x) = 3{x^2} + 1$</p>
<p>f'(x) is bijective function</p>
<p>and $f(g(x)) = x \Rightarrow g(x)$ is inverse of f(x)</p>
<p>$g(f(x)) = x$</p>
<p>$g'(f(x))\,.\,f'(x) = 1$</p>
<p>$g'(f(x)) = {1 \over {3{x^2} + 1}}$</p>
<p>Put x = 4 we get</p>
<p>$g'(63) = {1 \over {49}}$</p>
About this question
Subject: Mathematics · Chapter: Differentiation · Topic: Derivatives of Standard Functions
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