If y = 3 cos(x/3), find dy/dx when x = (3π/2)

  • A 1
  • B -3
  • C 2
  • D -1
jamb 2004mathematics

The correct answer is D. -1

Given that y = 3 cos(x/3), we can find the derivative of y with respect to x, dy/dx, using the chain rule.

The derivative of cos(x/3) with respect to x is -sin(x/3) (1/3), so the derivative of y with respect to x is dy/dx = 3 (-sin(x/3) (1/3)) = -sin(x/3).

When x = (3π/2), dy/dx = -sin((3π/2)/3) = -sin(π/2) = -1.

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