$\displaystyle Z=4x^2+9y^2$

$\displaystyle y^2=-\frac{4}{9}x^2$

How to draw a graph ?

Sqare root turns out to be negative.

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- Feb 12th 2007, 09:03 AMtotalnewbieDrawing a graph of function F(x,y)
$\displaystyle Z=4x^2+9y^2$

$\displaystyle y^2=-\frac{4}{9}x^2$

How to draw a graph ?

Sqare root turns out to be negative. - Feb 12th 2007, 10:27 AMThePerfectHacker
This one is a

**parabolid**which opens up on the z-axis.

Quote:

$\displaystyle y^2=-\frac{4}{9}x^2$

If x>0 or x<0 then we have a problem because the RHS is negative. Thus, x=0, in that case y=0 too. But there is no restriction on z, thus we move along the z-axis, thus we have a line, in fact, the z-axis.