Applications of Derivatives — Maths STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceMathsApplications of Derivatives1 Mark
Question
Show that the function $f(x)=x^3+10 x+7$ for $x \in \mathrm{R}$ is strictly increasing.
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Answer
Given that $f(x)=x^3+10 x+7$ Differentiate w. r. t. $x$. $ f^{\prime}(x)=3 x^2+10 $ Here, $3 x^2 \geq 0$ for all $x \in \mathrm{R}$ and $10>0$. $ \therefore 3 x^2+10>0 \Rightarrow f^{\prime}(x)>0 $ Thus $f(x)$ is a strictly increasing function.
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