If y = 2x - sin2x, find dy/dx when x = π/4
...If y = 2x - sin2x, find dy/dx when x = π/4
π
-π
π/2
-π/2
Correct answer is D
y = 2x cos2x - sin2x
dy/dx = 2 cos2x +(-2x sin2x) - 2 cos2x
= 2 cos2x - 2x sin2x - cos2x
= -2x sin2x
= -2 x (π/4) sin2 x (π/4)
= -(π/2) x 1 = -(π/2)