Answer:
D. pi
Step-by-step explanation:
Circumference of a circle = 
Diameter = d
Therefore, ratio of circumference of a circle to its diameter would be:

=> (d cancels d)
Therefore, the ratio of the circumference of a circle to its diameter is 
Answer:
Dividing exponents you subtract.
3^8/3^5 = 3^3
3^3
Multiplying exponents when an exponent is raised to another.
(3^3)^3 = <u>3^9</u>
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Final Answer is 
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Apparently this makes no sense according to comments, if you want a more indepth look into exponents search "The properties of exponents".
Circumference
C = pi d
C = 3.14 x 10
C = 31.4 cm
Area
A = pi r^2
A = 3.14 x 5^2
A = 78.5 cm^2
Answer:
no
Step-by-step explanation:
5 books are $2.50, mean that 10 books should only be $4.00 not $4.50. Also making the 15 for $6.00 only $5.50. All because 5 books would be $2.50.
Answer:
x² + 4x + 20 = 12x - 5
x² + 4x - 12x + 20 + 5 = 0
x² - 8x + 25 = 0
Δ = √b² - 4ac
= √(-8)² - 4×1×25
= √64-100
= √(-36)
x ∉ R