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QJEEM23Ma3aa1: JEE Main 2023 Mathematics - Class 12 JEEM23Ma3aa1 Solution: Let and . Then

Let f(x)=2x+tan⁡−1xf(x) = 2x + {\tan ^{ - 1}}x and g(x)=log⁡e(1+x2+x),x∈[0,3]g(x) = {\log _e}(\sqrt {1 + {x^2}} + x),x \in [0,3] . Then

Multiple Choice Options

  • A there exists x^∈[0,3]\widehat x \in [0,3] such that f′(x^)<g′(x^)f'(\widehat x) < g'(\widehat x)
  • B there exist 0<x1<x2<30 < {x_1} < {x_2} < 3 such that f(x)<g(x),∀x∈(x1,x2)f(x) < g(x),\forall x \in ({x_1},{x_2})
  • C min⁡f′(x)=1+max⁡g′(x)\min f'(x) = 1 + \max g'(x)
  • D max⁡f(x)>max⁡g(x)\max f(x) > \max g(x)

Step-by-Step Verified Solution

amp;f′(x)=2+11+x2,g′(x)=1x2+1amp;f′′(x)=−2x(1+x2)2lt;0amp;g′′(x)=−12(x2+1)−3/2⋅2xlt;0amp;f′(x)∣min⁡=f′(3)=2+110=2110amp;g′(x)∣max⁡=g′(0)=1amp;f′(x)∣max⁡=f(3)=2+tan⁡−13amp;g(x)∣max⁡=g(3)=ln⁡(3+10)lt;ln⁡lt;7lt;2\begin{aligned}&amp; f^{\prime}(x)=2+\frac{1}{1+x^2}, g^{\prime}(x)=\frac{1}{\sqrt{x^2+1}} \\\\&amp; f^{\prime \prime}(x)=-\frac{2 x}{\left(1+x^2\right)^2}&lt;0 \\\\&amp; g^{\prime \prime}(x)=-\frac{1}{2}\left(x^2+1\right)^{-3 / 2} \cdot 2 x&lt;0 \\\\&amp; \left.f^{\prime}(x)\right|_{\min }=f^{\prime}(3)=2+\frac{1}{10}=\frac{21}{10} \\\\&amp; \left.g^{\prime}(x)\right|_{\max }=g^{\prime}(0)=1 \\\\&amp; \left.f^{\prime}(x)\right|_{\max }=f(3)=2+\tan ^{-1} 3 \\\\&amp; \left.g(x)\right|_{\max }=g(3)=\ln (3+\sqrt{10})&lt;\ln &lt;7&lt;2\end{aligned}

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