If n is an integer such that n>1 and f(x)=(sin(n*x))^n, what is f'(x)?

Let us denote sin(nx) = u(x), where u is a function of x. The equation is now therefore f(x) =(u(x))^n.

For simplicity, we will write that as f(x) = u^n

By the chain rule, we know that f'(x) = df/dx = (df/du)*(du/dx).

Firstly computing df/du, we find df/du = n*u^(n-1)

Now we need to find du/dx. Since u = sin(nx) , du/dx = ncos(nx).

Therefore, our answer is f'(x) = (df/du)(du/dx) = nu^(n-1)*ncos(nx), 

subbing in u = sin(nx) yields the final answer:

f'(x) = n(sin(nx))^(n-1)*ncos(nx)

NT

Related Maths A Level answers

All answers ▸

Using transformation rules and your knowledge of trigonometric functions, draw the graph y=2sin(2x)


Find ∫(8x^3 + 4) dx


A curve passes through the point (4, 8) and satisfies the differential equation dy/dx = 1/ (2x + rootx) , Use a step-by-step method with a step length of 0.3 to estimate the value of y at x = 4.6 . Give your answer to four decimal places.


How is the factor theorem used?