Spot the wrong step in the derivative

Exercise and reference answers

Questions

1. Statement parts

   1. d/dx[sin(2x)]
   2. =
   3. cos(2x)
   4. ·
   5. 1

   Correction

   Chain rule needs the inner derivative; the factor is 2, not 1, so the answer is 2·cos(2x).

   Incorrect part

   1

2. Statement parts

   1. d/dx[ln(3x)]
   2. =
   3. 1/(3x)
   4. ·
   5. 3
   6. =
   7. 3/x

   Correction

   (1/(3x))·3 simplifies to 1/x, not 3/x.

   Incorrect part

   3/x