1. Determine the restrictions on the constants A, C and D so that Ax^2+Cy^2+Dx+Ey+F=0 represents a parabola that opens to the left. I know that A=0, how do u know if CD>0 or CD<0..........?? 2. The equation Ax^2+By^2+Cy=0 represents an ellipse. If 0<A<B<C, then the vertices of the ellipse are on a line parallel to the y-axis or a line parallel to the x-axis???? 3. Determine the restrictions on the constants, A, C and E such that the following equation is a parbola with a vertical axis of symmetry. Ax^2+Cy^2+x+Ey=0 i know that A can't =0 and C=0... how can u tell if E=0 or not....??? Thanks.