Q64 / 155 · WBJEE 2022 · Mathematics

Let $f(x)=(x-2)^{17}(x+5)^{24}$. Then

  • A
    $f$ does not have a critical point at $x=2$
  • B
    $f$ has a minimum at $x=2$
  • Correct answer
    C
    $f$ has neither a maximum nor a minimum at $x=2$
  • D
    f has a maximum at $x=2$

Solution

$\begin{aligned} & f(x)=(x-2)^{17}(x+5)^{24} \\ \Rightarrow & f^{\prime}(x)=17(x-2)^{16}(x+5)^{24}+24(x-2)^{17}(x+5)^{23}=(x-2)^{16}(x+5)^{23}(17 x+85+24 x-48)=(x-2)^{16}(x+5)^{23}(41 x+37) \end{aligned}$ Figure

Hence, the correct answer is option: 'C'.

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