f(x) = 2x + sin(2x)
f ' (x) = 2 + 2cos(2x)
= 0
2cos(2x) = -2
cos 2x = -1
I know cos π = -1
so 2x = π
x = π/2
Find the x-coordinates where f '(x) = 0 for f(x) = 2x + sin(2x) in the interval [0, 2π].
2 answers
cos(3π) is also -1, so x = 3π/2
1 answer