Question $14$

By setting one variable constant, find a plane that intersects the graph of $z=-49x^2+y^2-7$ in each of the followings:

a$)$ Parabola opening upward: The intersecting plane is $$

b$)$ Parabola opening the right: The intersecting plane is $$

The equation of the intersecting curve is $$

c$)$ Pair of intersecting straight lines: The intersecting plane is $$

Equations of intersecting lines $y=$