You need to know these two formulas:

For example,

Answer:
=376.8 
Step-by-step explanation:
V=n
Where V is the volume , r is the radius and h is the perpendicular height .
r =
m=6
h = 10m
n=3.14
v= 3.14 * 6*6 *
=376.8 
Regular Pirce = $80.
Discount = 20%
Discount = 20% x $80 = 0.2 x 80 = $16
Sale Price = 80 - 16 = $64
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Answer: The Sale Price is $64.
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9. D because it fits the description when it is graphed.
11. D because it has the correct vertex, which is (1.5, 4.75).
12. f(x)=-4(x-2)²+16 works with the table and provided graph!
13. 0 isn't a zero for f(x), so B is correct (the zeros are 1/2 and 4).
14. The width is about 3.831.
15. The answer is B because the equation for a parabola in this form is:
f(x) = (x - r₁)(x - r₂)
Every one of these except for 15 was solved using desmos, a graphing calculator.
Hope this helps!