Answer:
First option: 
Second option: 
Fourth option: 
Step-by-step explanation:
Rewrite each equation in the form
and then use the Discriminant formula for each equation. This is:

1) For
:

Then:
Since
this equation has no real solutions, but has two complex solutions.
2) For
:

Then:
Since
this equation has no real solutions, but has two complex solutions.
3) For
:

Then:
Since
this equation has one real solution.
4) For
:
Then:
Since
, this equation has no real solutions, but has two complex solutions.
Answer: 28.26
Step-by-step explanation:
What your looking for is called the annulus (or the difference of two concentric circles). You can find the annulus by subtracting the area of the inner circle from the area of the outer circle. Volume of a circle= πr²
You are given the diameter in these problems, so you need radius.
For the first circle (8 in one) :
8/2=4 r=4
A=3.14(4)²
A=50.24
For the second one (10 in one) :
10/2=5 r=5
A=3.14(5)²
A=78.5
To find the measure of the annulus, you subtract those numbers, getting 28.26
8 is the answer to your question
No, she's not. If each energy drink's unit cost was just over $2.00, and there are 6 drinks in a pack, then that's at least $12.00 right there, but the entire 6-pack is on sale for only $2.99. She should find the correct price by dividing $2.99/6, resulting in about $0.50 per drink