Explain which operation to use to solve the following problem. Then, solve the problem.

The volume of a cylinder is represented by the polynomial 2x3+5x2+3x+18
. The height of the cylinder is represented by the polynomial x+3
. What expression represents the area of the base of the cylinder?

(2 points)

1 answer

To find the area of the base of a cylinder given the volume and height, you can use the formula for the volume of a cylinder:

\[ \text{Volume} = \text{Base Area} \times \text{Height} \]

From the problem, we know the volume of the cylinder is represented by the polynomial:

\[ V = 2x^3 + 5x^2 + 3x + 18 \]

And the height of the cylinder is represented by the polynomial:

\[ h = x + 3 \]

To find the area of the base, we need to solve for the base area (B) using the formula:

\[ B = \frac{V}{h} \]

We will divide the polynomial representing the volume \( V \) by the polynomial representing the height \( h \):

\[ B = \frac{2x^3 + 5x^2 + 3x + 18}{x + 3} \]

Now, we will perform polynomial long division.

  1. Divide the first term of the numerator by the first term of the denominator:

\[ \frac{2x^3}{x} = 2x^2 \]

  1. Multiply \( 2x^2 \) by the entire denominator \( x + 3 \):

\[ 2x^2(x + 3) = 2x^3 + 6x^2 \]

  1. Subtract this result from the original polynomial:

\[ (2x^3 + 5x^2 + 3x + 18) - (2x^3 + 6x^2) = -x^2 + 3x + 18 \]

  1. Now, divide the first term of the new polynomial by the first term of the denominator again:

\[ \frac{-x^2}{x} = -x \]

  1. Multiply \(-x\) by the entire denominator:

\[ -x(x + 3) = -x^2 - 3x \]

  1. Subtract this from the result we got in the previous step:

\[ (-x^2 + 3x + 18) - (-x^2 - 3x) = 6x + 18 \]

  1. Now, divide the first term of the new polynomial \( 6x + 18 \) by the first term of the denominator:

\[ \frac{6x}{x} = 6 \]

  1. Multiply \( 6 \) by the entire denominator:

\[ 6(x + 3) = 6x + 18 \]

  1. Subtract this from \( 6x + 18 \):

\[ (6x + 18) - (6x + 18) = 0 \]

Thus, there is no remainder. The entire expression simplifies to:

\[ B = 2x^2 - x + 6 \]

So, the expression that represents the area of the base of the cylinder is:

\[ \boxed{2x^2 - x + 6} \]