Suppose the function f is differentiable everywhere, and the graph of 

y = f(x)

 always lies above the x-axis and never has a horizontal tangent. For what value of y is the rate of change of 

y^3

 with respect to x seventy-five times the rate of change of y with respect to x?


이 문제는 이해가 안돼요 ㅠㅠ 도와주세요



Find the x-coordinates of all points on the curve 

f(x) = sin(2x) − 2 sin(x)

 at which the tangent line is horizontal. (Enter your answers as a comma-separated list. Use n to represent any integer.)

이 문제는 미분하고 0되는거 찾으면 되는거 같은데 답이 틀렸다고 나오네요 ㅠㅠ