Question #d9dbd

1 Answer
Dec 13, 2016

d/dxlog(x-2) = 1/(x-2)

Explanation:

This answer supposes log(x) refers to the natural (base-e) logarithm.*

Using the chain rule and the derivative of log(x):

The chain rule, together with the known derivative d/dxlog(x) = 1/x, gives us

d/dxlog(x-2) = 1/(x-2)(d/dx(x-2))

=1/(x-2)(1)

=1/(x-2)

Using implicit differentiation and the derivative of e^x:

If we do not know the derivative of log(x), but do know the derivative d/dxe^x = e^x, we can first create and modify an equation and use implicit differentiation:

Let y = log(x-2)

=> e^y = e^log(x-2)

=> e^y = x-2

=> d/dxe^y = d/dx(x-2)

=> e^ydy/dx = 1

=> dy/dx = 1/e^y

=1/e^(log(x-2))

=1/(x-2)


*If the intended logarithm is base-10, rather than the natural logarithm, then a coefficient of 1/ln(10) should be included in the answer, as converting to the natural logarithm would give log_10(x) = ln(x)/ln(10), and then the process would proceed as above.