Second order partial derivatives using quotient rule

[VooDoo]

Hi guys,

I have the following question for a uni assignment, I have done part A and found the stationary points to be at

x=-2 x = 2
y=-1 y=1

Not sure if it is correct though.

I did this by using finding the partial derivatives using the quoitent rule, then making the partial derivatives equal to zero and solving for x and y. Now the second part of the question asks to find the second order DE, which would be an absolute pain to do using the quoitent rule. I am really, really lost guys.

 

[arildno]

Whatever does the vertical line segment in the numerator signify??

 

[VooDoo]

Whatever does the vertical line segment in the numerator signify??

i think its a full stop that shouldn't be there