Question
The function $f$ defined by $f(x)=4 x^4-2 x+1$ is increasing for

Answer

(d) : We have, $f(x)=4 x^4-2 x+1 \Rightarrow f^{\prime}(x)=16 x^3-2$
The function is increasing if $f^{\prime}(x)>0$
$
\Rightarrow 16 x^3-2>0 \Rightarrow x>\frac{1}{2}
$

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