# What are the extrema and saddle points of #f(x,y) = 2x^(2) + (xy)^2 + 5x^2 - y/x#?

##### 1 Answer

#### Answer:

This function has **no stationary points** (are you sure that

#### Explanation:

According to the most diffused definition of *saddle points* (stationary points that are not extrema), you are searching for the stationary points of the function in its domain

We can now rewrite the expression given for

The way to identify them is to search for the points that nullify the gradient of

Since the domain is an open set, we don't need to search for extrema eventually lying on the boundary, because an open sets contain no boundary points.

So let's compute the gradient of the function:

This is null when the following equations are simultaneously satisfied:

We can turn the second into

This can't be satisfied for