I have this function again:

The value of

when

and

is

.

The maximum percentage error in the value of

is

% and the maximum percentage error in the value of

is

%.

I have to find the least and greatest possible values that

can take, and the maximum possible percentage error in taking the value

.

I plugged

and

into the partial derivatives:

x y
And then found:

So the least and greatest possible values for

are

and

, and the maximum possible percentage error is

% ?

Is there anything correct here or am I completely wrong?