MCQ
Let $f(x) = (x-4)(x-5)(x-6)(x-7)$ then -
  • A
    $f'(x) = 0$ has four roots
  • Three roots of $f'(x) = 0$ lie in $(4, 5)  \cup  (5, 6)  \cup  (6, 7)$
  • C
    The equation $f'(x) = 0$ has only one root
  • D
    Three roots of $f'(x) = 0$ lie in $(3, 4)  \cup  (4, 5)  \cup  (5, 6)$

Answer

Correct option: B.
Three roots of $f'(x) = 0$ lie in $(4, 5)  \cup  (5, 6)  \cup  (6, 7)$
b

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