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QJEEM24Mabad3: JEE Main 2024 Mathematics - Class 12 JEEM24Mabad3 Solution: If , then is equal to :

If y=(x+1)(x2−x)xx+x+x+115(3cos⁡2x−5)cos⁡3xy=\frac{(\sqrt{x}+1)\left(x^2-\sqrt{x}\right)}{x \sqrt{x}+x+\sqrt{x}}+\frac{1}{15}\left(3 \cos ^2 x-5\right) \cos ^3 x , then 96y′(π6)96 y^{\prime}\left(\frac{\pi}{6}\right) is equal to :

Step-by-Step Verified Solution

amp;y=(x+1)(x2−x)xx+x+x+115(3cos⁡2x−5)cos⁡3xamp;y=(x+1)(x)((x)3−1)(x)((x)2+(x)+1)+15cos⁡5x−13cos⁡3xamp;y=(x+1)(x−1)+15cos⁡5x−13cos⁡3x\begin{aligned} & y=\frac{(\sqrt{x}+1)\left(x^2-\sqrt{x}\right)}{x \sqrt{x}+x+\sqrt{x}}+\frac{1}{15}\left(3 \cos ^2 x-5\right) \cos ^3 x \\\\ & y=\frac{(\sqrt{x}+1)(\sqrt{x})\left((\sqrt{x})^3-1\right)}{(\sqrt{x})\left((\sqrt{x})^2+(\sqrt{x})+1\right)}+\frac{1}{5} \cos ^5 x-\frac{1}{3} \cos ^3 x \\\\ & y=(\sqrt{x}+1)(\sqrt{x}-1)+\frac{1}{5} \cos ^5 x-\frac{1}{3} \cos ^3 x\end{aligned}

amp;y′=1−cos⁡4x⋅(sin⁡x)+cos⁡2x(sin⁡xamp;y′(π6)=1−916×12+34×12amp;=32−9+1232=3532amp;∴96y′(π6)=105\begin{aligned} & y^{\prime}=1-\cos ^4 x \cdot(\sin x)+\cos ^2 x(\sin x \\\\ & y^{\prime}\left(\frac{\pi}{6}\right)=1-\frac{9}{16} \times \frac{1}{2}+\frac{3}{4} \times \frac{1}{2} \\\\ & =\frac{32-9+12}{32}=\frac{35}{32} \\\\ & \therefore 96 y^{\prime}\left(\frac{\pi}{6}\right)=105\end{aligned}

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