PYQ Vault
EbooksTutor

f(x) = cos x cos 2x cos 4x cos 8x cos 16x: find f'(pi/4)

The same question, asked 2 times: 17 Apr 2026 S1, 17 Apr 2026 S2. Every wording below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    17 Apr 2026 S1

    73
    If f(x)=cos⁡xcos⁡2xcos⁡4xcos⁡8xcos⁡16xf(x) = \cos x\cos 2x\cos 4x\cos 8x\cos 16x, then f′(π4)f'\left(\dfrac{\pi}{4}\right) is equal to

    Tap an option to check your answer.

  2. Question 2

    17 Apr 2026 S2

    69
    If f(x)=cos⁡x cos⁡2x cos⁡4x cos⁡8x cos⁡16xf(x) = \cos x\ \cos 2x\ \cos 4x\ \cos 8x\ \cos 16x, then f′(π4)=f'\left(\dfrac{\pi}{4}\right) =

    Tap an option to check your answer.