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Which number is rational?

A. [tex]\(-3 \frac{1}{2}\)[/tex]
B. [tex]\(\sqrt{5}\)[/tex]
C. [tex]\(\pi\)[/tex]
D. [tex]\(9.23157 \ldots\)[/tex]

Sagot :

Sure, let's determine which of these numbers is rational.

First, recall the definition of a rational number. A rational number is any number that can be expressed as the quotient or fraction [tex]\(\frac{a}{b}\)[/tex] of two integers, where [tex]\(a\)[/tex] (the numerator) and [tex]\(b\)[/tex] (the denominator) are integers, and [tex]\(b \neq 0\)[/tex].

Now, let's analyze each number provided:

1. [tex]\( -3 \frac{1}{2} \)[/tex]

This is a mixed number. A mixed number can be expressed as an improper fraction.

[tex]\[ -3 \frac{1}{2} = -\left(3 + \frac{1}{2}\right) = -\left(\frac{6}{2} + \frac{1}{2}\right) = -\frac{7}{2} \][/tex]

Since [tex]\(-\frac{7}{2}\)[/tex] is a fraction of two integers, it is a rational number.

2. [tex]\( \sqrt{5} \)[/tex]

The square root of 5 is an irrational number because it cannot be expressed as a simple fraction. It is a non-repeating, non-terminating decimal. Thus, [tex]\( \sqrt{5} \)[/tex] is not rational.

3. [tex]\( \pi \)[/tex]

Pi ([tex]\(\pi\)[/tex]) is a well-known irrational number. It cannot be expressed as a fraction of two integers and its decimal representation is non-terminating and non-repeating. Therefore, [tex]\(\pi\)[/tex] is not a rational number.

4. [tex]\( 9.23157 \ldots \)[/tex]

The number [tex]\( 9.23157 \ldots \)[/tex] appears with an ellipsis, indicating it is a non-terminating decimal. Without any repeating pattern, it cannot be expressed as a fraction of two integers, making it an irrational number.

To summarize, the only rational number among the given options is:

[tex]\[ -3 \frac{1}{2} \][/tex]