Solve the following problem and select your answer from the choices given.

The formula for the volume of a right circular cylinder is [tex]V = \pi r^2 h[/tex]. If [tex]r = 2b[/tex] and [tex]h = 5b + 3[/tex], what is the volume of the cylinder in terms of [tex]b[/tex]?

A. [tex]10 \pi b^2 + 6 \pi b[/tex]
B. [tex]20 \pi b^3 + 12 \pi b^2[/tex]
C. [tex]20 \pi^2 b^3 + 12 \pi^2 b^2[/tex]
D. [tex]50 \pi b^3 + 20 \pi b^2 + 90 \pi b[/tex]



Answer :

Let's start by substituting the given expressions for [tex]\( r \)[/tex] and [tex]\( h \)[/tex] into the formula for the volume of a right circular cylinder.

The volume [tex]\( V \)[/tex] of a cylinder is given by the formula:
[tex]\[ V = \pi r^2 h \][/tex]

We have:
[tex]\[ r = 2b \][/tex]
[tex]\[ h = 5b + 3 \][/tex]

First, substitute [tex]\( r = 2b \)[/tex] into the formula:
[tex]\[ V = \pi (2b)^2 h \][/tex]

Simplify [tex]\( (2b)^2 \)[/tex]:
[tex]\[ (2b)^2 = 4b^2 \][/tex]

Thus, the volume formula becomes:
[tex]\[ V = \pi \cdot 4b^2 \cdot h \][/tex]

Next, substitute [tex]\( h = 5b + 3 \)[/tex] into the volume formula:
[tex]\[ V = \pi \cdot 4b^2 \cdot (5b + 3) \][/tex]

Distribute [tex]\( 4b^2 \)[/tex] within the parentheses:
[tex]\[ V = \pi \cdot (4b^2 \cdot 5b + 4b^2 \cdot 3) \][/tex]
[tex]\[ V = \pi \cdot (20b^3 + 12b^2) \][/tex]

Distribute [tex]\(\pi\)[/tex] throughout the terms:
[tex]\[ V = 20 \pi b^3 + 12 \pi b^2 \][/tex]

Therefore, the volume [tex]\( V \)[/tex] of the cylinder in terms of [tex]\( b \)[/tex] is:
[tex]\[ 20 \pi b^3 + 12 \pi b^2 \][/tex]

Hence, the correct answer is:
[tex]\[ 20 \pi b^3 + 12 \pi b^2 \][/tex]