Answered

A square concert stage in the center of a fairground has an area of [tex][tex]$4x^2 + 12x + 9 \, \text{ft}^2$[/tex][/tex]. The dimensions of the stage have the form [tex][tex]$cx + d$[/tex][/tex], where [tex][tex]$c$[/tex][/tex] and [tex][tex]$d$[/tex][/tex] are whole numbers.

Find an expression for the perimeter of the stage. What is the perimeter when [tex][tex]$x = 2 \, \text{ft}$[/tex][/tex]?



Answer :

To solve this problem, we need to determine a few key expressions related to the square concert stage.

### Step-by-Step Solution

1. Represent the Area Expression:

We are given the area of the square stage as:
[tex]\[ 4x^2 + 12x + 9 \text{ square feet} \][/tex]

2. Identify the Side Length of the Square:

For a square, the area [tex]\(A\)[/tex] is given by the side length squared. Hence, we need to express the given area expression in the form [tex]\( (cx + d)^2 \)[/tex].

Notice that:
[tex]\[ (2x + 3)^2 = (2x + 3)(2x + 3) = 4x^2 + 12x + 9 \][/tex]

Therefore, the side length of the square stage is:
[tex]\[ 2x + 3 \text{ feet} \][/tex]

3. Find the Perimeter of the Square:

The perimeter [tex]\(P\)[/tex] of a square is four times the side length. Thus:
[tex]\[ P = 4 \times \text{side length} = 4 \times (2x + 3) \][/tex]

4. Simplify the Perimeter Expression:

Simplifying this we get:
[tex]\[ P = 4 \times (2x + 3) = 8x + 12 \text{ feet} \][/tex]

5. Determine the Perimeter for [tex]\(x = 2\)[/tex]:

We substitute [tex]\(x = 2\)[/tex] into the perimeter expression:
[tex]\[ P = 8(2) + 12 = 16 + 12 = 28 \text{ feet} \][/tex]

### Summary

- Expression for the Perimeter:
[tex]\[ 8x + 12 \text{ feet} \][/tex]

- Perimeter when [tex]\(x = 2\)[/tex]:
[tex]\[ 28 \text{ feet} \][/tex]

Thus, the perimeter of the square concert stage when [tex]\(x = 2\)[/tex] feet is 28 feet.