CONTINUITY AND DIFFERENTIABILITY — MATHS STD 12 Science — Question
Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSCONTINUITY AND DIFFERENTIABILITY3 Marks
Question
Differentiate w.r.t. x the function in Exercise:
$(5\text{x})^{3\cos2\text{x}}$
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Answer
Let $\text{y}=(5\text{x})^{3\cos2\text{x}}$ Taking logaritthm on both the sides, we obtain $\log\text{y}=3\cos2\text{x}\log5\text{x}$ Differentiating both sides with respect to x, we obtain$\frac{1}{\text{y}}\frac{\text{dy}}{\text{dx}}=3\Big[\log5\text{x}.\frac{\text{d}}{\text{dx}}(\cos2\text{x})+\cos2\text{x}.\frac{\text{d}}{\text{dx}}(\log5\text{x})\Big]$
$\Rightarrow\ \frac{\text{dy}}{\text{dx}}=3\text{x}\Big[\log5\text{x}(-\sin2\text{x}).\frac{\text{d}}{\text{dx}}(2\text{x})+\cos2\text{x}.\frac{1}{5\text{x}}.\frac{\text{d}}{\text{dx}}(5\text{x})\Big]$
$\Rightarrow\ \frac{\text{dy}}{\text{dx}}=3\text{y}\Big[-2\sin2\text{x}\log5\text{x}+\frac{\cos2\text{x}}{\text{x}}\Big]$
$\Rightarrow\ \frac{\text{dy}}{\text{dx}}=3\text{y}\Big[\frac{3\cos2\text{x}}{\text{x}}-6\sin2\text{x}\log5\text{x}\Big]$ $\Rightarrow\ \frac{\text{dy}}{\text{dx}}=(5\text{x})^{\text{x}\cos2\text{x}}\Big[\frac{3\cos2\text{x}}{\text{x}}-6\sin2\text{x}\log5\text{x}\Big]$
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