# What is the equation of the normal line of #f(x)=x/lnx# at #x=4 #?

##### 1 Answer

Feb 17, 2016

#### Explanation:

First of all, we need a point of intersection. We know the line will intersect

So we know at least

Next we need the gradient of the line and this is obtained by taking the derivative of

Now find

Thus we have the gradient of the line.

Now substitute into the formula:

We can better visualise this from the graphs of the function: