Find the absolute maximum of $x^{40}-x^{20}$ on the interval $[0,1]$.

Find the absolute maximum of $x^{40}-x^{20}$ on the interval $[0,1]$.
  1. $\frac{-1}{4}$
  2. 0
  3. $\frac{1}{4}$
  4. $\frac{1}{2}$

Solution

Let $ \begin{aligned} f(x) & =x^{40}-x^{20} \\ f^{\prime}(x) & =40 x^{39}-20 x^{19} \\ f^{\prime}(x) & =0 \Rightarrow 20 x^{19}\left(2 x^{20}-1\right)=0 \\ x & =0, x=1 \\ f(0) & =0 \\ f(1) & =0 \end{aligned} $ $\therefore$ Maximum value of $x^{40}-x^{20}$ in $[0,1]$ is 0

Asked in: AP EAMCET 2021 (25 Aug Shift 1)

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