Differentiate y=ln(ln(x)) with respect to x.

To solve this question we need to understand the process of implicit differentiation, which is a case of using the chain rule. If you remember the chain rule states that for y=f(g(x)), we have y'=f'(g(x))g'(x), so that we treat y as being composed of two functions and differentiate them individually, then multiply. So instead if we have f(y)=g(x), then using the same rule on the left hand side but with y, and differentiating both sides we get y'f'(y)=g'(x). Now that this is understood we can solve the question. We are given y=ln(ln(x)) so ey = ln(x). Now differentiate this on both sides: y'ey=1/x. Now we're looking for y' on one side and everything else on the other:y'=1/(xey). We're almost there but there's a problem, we want y' with respect to x so we need the right hand side only with x: fortunately we know ey=lnx, so y'=1/(xln(x)). And we are done. Can you differentiate y = ln(ln(x2)) for me?

MK

Related Maths A Level answers

All answers ▸

Integrate sin7xcos3x


Express 4sin(x)+6cos(x) in terms of Rsin(x+a) where R and a are constants to be determined (a should be given in rad).


Complete the indefinite integral : ∫x lnx dx


A block of mass 5kg is at rest on a smooth horizontal table, and connected to blocks of 3kg and 4kg which are hanging by strings via pulleys on either end of the table. Find the acceleration of the system and the tension in each string.