A rectangle has sides whose lengths in units are represented by polynomials as shown where x is a positive integer

3/2x+3
3x-1/2
Which expression represents the perimeter of the rectangle in units
A. 9/2x+5/2

1 answer

To find the perimeter \( P \) of a rectangle given by the side lengths represented by two polynomials, we can use the formula for perimeter:

\[ P = 2 \times (\text{length} + \text{width}) \]

In this case, the lengths of the sides are represented as:

  • Length \( L = \frac{3}{2}x + 3 \)
  • Width \( W = 3x - \frac{1}{2} \)

Now let's find \( L + W \):

\[ L + W = \left( \frac{3}{2}x + 3 \right) + \left( 3x - \frac{1}{2} \right) \]

Combining the terms:

  1. Combine the \( x \) terms: \[ \frac{3}{2}x + 3x = \frac{3}{2}x + \frac{6}{2}x = \frac{9}{2}x \]

  2. Combine the constant terms: \[ 3 - \frac{1}{2} = \frac{6}{2} - \frac{1}{2} = \frac{5}{2} \]

So we have:

\[ L + W = \frac{9}{2}x + \frac{5}{2} \]

Now, we need to calculate the perimeter:

\[ P = 2 \times (L + W) = 2 \times \left( \frac{9}{2}x + \frac{5}{2} \right) \]

Distributing the 2:

\[ P = 2 \times \frac{9}{2}x + 2 \times \frac{5}{2} \] \[ P = 9x + 5 \]

Thus, the expression that represents the perimeter of the rectangle is:

\[ P = 9x + 5 \]

None of the options provided match this, but it appears the expression listed as option A, \( \frac{9}{2}x + \frac{5}{2} \), is not correct as it does not correctly represent the perimeter. The correct perimeter expression is \( 9x + 5 \).