Answer:
Here's what I get
Step-by-step explanation:
The formula for a quadratic equation is
ax² + bx + c = 0
The quadratic formula gives the roots:

D is the discriminant.
It tells us the number of roots to the equation — the number of times the graph crosses the x-axis.

It doesn't matter if the graph opens upwards or downwards.
If D > 0, the graph crosses the x-axis at two points.
If D = 0, the graph touches the x-axis at one point.
If D < 0, the graph never reaches the x-axis.
Your graph must look like one of the two graphs on the right in the Figure below.
It whould be -1.5 for and 0.5
If there is such a scalar function <em>f</em>, then



Integrate both sides of the first equation with respect to <em>x</em> :

Differentiate both sides with respect to <em>y</em> :


Integrate both sides with respect to <em>y</em> :

Plug this into the equation above with <em>f</em> , then differentiate both sides with respect to <em>z</em> :



Integrate both sides with respect to <em>z</em> :

So we end up with

Concave up is U-shaped.
There will be a inflection/critical point f'(x) =0 then a negative slope f'(x) = neg then another inflection/critical point f'(x) =0 at the bottom of the U-shape then a positive slope to last inflection/critical point. The interval for the Concave Up shape is the first and last inflection points.