Simplify the following mathematical expressions:

\begin{tabular}{|c|c|}
\hline
Model & Expression \\
\hline
1 & [tex]$4 + 5$[/tex] \\
\hline
2 & [tex]$4(5)$[/tex] \\
\hline
3 & 20 \\
\hline
4 & [tex]$5(4)$[/tex] \\
\hline
5 & [tex]$b(5)$[/tex] \\
\hline
\end{tabular}

Which expressions represent this model? Check all that apply.



Answer :

Let's go through each expression step by step to determine its correctness and whether it matches the given model. Based on the numerical results provided, here's the detailed solution:

1. Expression [tex]\(4 + 5\)[/tex]:
- When we evaluate [tex]\(4 + 5\)[/tex], we get [tex]\(9\)[/tex].
- Therefore, the numerical result for [tex]\(4 + 5\)[/tex] is [tex]\(9\)[/tex].
- This does not match with 20, so it does not represent the model.

2. Expression [tex]\(4(5)\)[/tex]:
- This expression is equivalent to [tex]\(4 \times 5\)[/tex].
- Evaluating [tex]\(4 \times 5\)[/tex] gives us [tex]\(20\)[/tex].
- Therefore, the numerical result for [tex]\(4(5)\)[/tex] is [tex]\(20\)[/tex].
- This matches with the model, so it does represent the model.

3. Expression [tex]\(20\)[/tex]:
- This value is given without the need for further calculation.
- The value is [tex]\(20\)[/tex].
- This directly matches the model, so it does represent the model.

4. Expression [tex]\(5(4)\)[/tex]:
- This expression is equivalent to [tex]\(5 \times 4\)[/tex].
- Evaluating [tex]\(5 \times 4\)[/tex] also gives us [tex]\(20\)[/tex].
- Therefore, the numerical result for [tex]\(5(4)\)[/tex] is [tex]\(20\)[/tex].
- This matches with the model, so it does represent the model.

5. Expression [tex]\(b(5)\)[/tex]:
- The variable [tex]\(b\)[/tex] is undefined in this context.
- Without knowing the value of [tex]\(b\)[/tex], we cannot evaluate this expression.
- For this reason, it is invalid and does not represent the model.

6. Expression [tex]\(lnfes\)[/tex]:
- This sequence of characters does not represent a recognizable mathematical expression or value.
- It appears nonsensical and cannot be evaluated.
- Therefore, it is invalid and does not represent the model.

Given the evaluations above, we check which expressions represent the given model:

- [tex]\(4 + 5\)[/tex]: Does not represent the model.
- [tex]\(4(5)\)[/tex]: Represents the model.
- [tex]\(20\)[/tex]: Represents the model.
- [tex]\(5(4)\)[/tex]: Represents the model.
- [tex]\(b(5)\)[/tex]: Does not represent the model.
- [tex]\(lnfes\)[/tex]: Does not represent the model.

Therefore, the expressions that represent the model are:

[tex]\[ 4(5), 20, \text{and} 5(4) \][/tex]