A rational number is a number that can be expressed as the quotient or fraction $\frac{a}{b}$ of two integers, where the denominator $b$ is not zero.
The square root of 32 is approximately 5.66, which cannot be expressed as a fraction of two integers.
The square root of 81 is exactly 9, which can be expressed as $\frac{9}{1}$.
The square root of 90 is approximately 9.49, which cannot be expressed as a fraction of two integers.
The cube root of 125 is exactly 5, which can be expressed as $\frac{5}{1}$.
Therefore, the only rational number among the given options is $\boxed{81\sqrt{}}$.
Which of the following is a rational number: 32−−√ , 81−−√ , 90−−√ , or 125−−−√ ?
1 answer