The following table shows the length and width of a rectangle:
\begin{tabular}{|l|l|l|}
\hline & Length & Width \\
\hline Rectangle A & [tex]$3x+5$[/tex] & [tex]$2x-3$[/tex] \\
\hline
\end{tabular}

Which expression represents the perimeter of Rectangle [tex]$A$[/tex] and demonstrates the closure property?

A. [tex]$10x+4$[/tex]; the answer is a polynomial
B. [tex]$2x+4$[/tex]; the answer is a polynomial
C. [tex]$10x+4$[/tex]; the answer may or may not be a polynomial
D. [tex]$2x+4$[/tex]; the answer may or may not be a polynomial



Answer :

Let's find the expression for the perimeter of rectangle [tex]\( A \)[/tex] and demonstrate its characteristics.

To determine the perimeter of a rectangle, we use the formula:

[tex]\[ \text{Perimeter} = 2 \times (\text{Length} + \text{Width}) \][/tex]

For rectangle [tex]\( A \)[/tex], the given lengths are:

- Length: [tex]\( 3x + 5 \)[/tex]
- Width: [tex]\( 2x - 3 \)[/tex]

First, add the length and width:

[tex]\[ \text{Length} + \text{Width} = (3x + 5) + (2x - 3) \][/tex]

Combine like terms:

[tex]\[ \text{Length} + \text{Width} = 3x + 2x + 5 - 3 = 5x + 2 \][/tex]

Now, multiply by 2 to find the perimeter:

[tex]\[ \text{Perimeter} = 2 \times (5x + 2) = 10x + 4 \][/tex]

Thus, the expression for the perimeter of rectangle [tex]\( A \)[/tex] is:

[tex]\[ 10x + 4 \][/tex]

Let's analyze the closure property and the characteristics of the expression. The closure property refers to the set being closed under a specific operation. In this case, addition and multiplication of polynomials result in another polynomial.

The expression [tex]\( 10x + 4 \)[/tex] is a polynomial because:

1. It is a sum of terms of the form [tex]\( ax^n \)[/tex] where [tex]\( a \)[/tex] is a coefficient and [tex]\( n \)[/tex] is a non-negative integer.
2. The operation of addition and multiplication performed here did not produce any terms that fall outside the definition of a polynomial.

Therefore, the expression [tex]\( 10x + 4 \)[/tex] satisfies the closure property and is indeed a polynomial.

The correct answer is:
[tex]\[ 10x + 4; \text{ the answer is a polynomial} \][/tex]