For the most part, the cross-section formed is a <em>trapezoid</em>, but if the slice passes through the apex of the pyramid, that shape is a <em>triangle</em>.
(Image source: MathCaptain.com)
The discriminant is the bit under the radical, the
.
Because it's under a radical, it's what tells you how many and what kind of solutions you have (two real, one real, or two imaginary/complex solutions).
Does that answer your question? Or do you need an example?
Suppose you had the equation
, then you'd have:
,
and 
You'd plug those values into
to see if the discriminant was positive, zero, or negative:

Since that is 37 (a postiive number), you'd have two real solutions.
1/9 because 5 shows up 4 times out of 36 times so that would be 4/36 and you would simplify it to get 1/9
(fill the answers in left from right in each line)
1. -20, -5, 10
2. -16, 0, 16, 32
3. -8, -6, -3
4. 0, 6, 18, 24
5. -12, 0, 16
Y has a bigger area, 660.185 while x is, 254.34
The difference is 405.845