Question
$2 x^3-6 x+5$ is an increasing function, if

Answer

$(c) :$ Let $f(x)=2 x^3-6 x+5$
On differentiating $\text{w.r.t. x}$, we get $f^{\prime}(x)=6 x^2-6$
Since, it is increasing function.
$\Rightarrow 6 x^2-6 > 0$
$\Rightarrow(x-1)(x+1)>0$
$\Rightarrow x > 1 \text { or } x<-1$

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