Application of Derivatives — MATHS STD 12 Science — Question
Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSApplication of Derivatives1 Mark
Question
The function $f(x)=x^3+3 x$ is increasing in interval
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Answer
f(x)=$x^3+3 x$ For increasing, we must have $f^{\prime}(x)>0$ $ \therefore f^{\prime}(x)=3 x^2+3>0 \Rightarrow 3\left(x^2+1\right)>0 $ $\Rightarrow x^2+1>0$, which is true $\forall x \in R$.
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