MCQ
The function $f(x) = 1 - {x^3} - {x^5}$ is decreasing for
  • A
    $1 \le x \le 5$
  • B
    $x \le 1$
  • C
    $x \ge 1$
  • All values of  $x$

Answer

Correct option: D.
All values of  $x$
d
(d) $f(x) = 1 - {x^3} - {x^5}$ ==> $f'(x) = - 3{x^2} - 5{x^4}$

$\therefore$ $f'(x) < 0$ for all values of  $x.$

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