Identifying and Classifying Critical Points

[jegues]

Homework Statement

Find all critical points of the function given.(see figure)

Choose and classify anyone critical point.

Homework Equations

The Attempt at a Solution

I found the following critical points,

(0,0), (0,-3), (3/2,3/2) and (-3/2, 3/2)

Wolfram alpha is telling me the critical points are (0,0) and (0,3). (We don't deal with critical points that have complex numbers in them).

I can't find my error.

Can anyone see it?

 

[vela]

You flipped a sign when you factored the y terms in equation (1).