Originally Posted by

**andreaspohle** True of False

The trace of x^2+2y^2 +10z^2=5 in the plane z=2 is an ellipse.

False because x^2+2y^2=-35 is an ellipse, so true is that correct?

Please do read the last line you wrote above and tell me if you really expect anyone but yourself to understand it: what are you asking there?? Is like the following:

Claim: A is B

Answer: False because A is B, so true is that correct?

Does this make any sense to you?

Btw, the answer is, of course, false, since sum of squares and positives cannot be a negative number

Tonio