To analyze which statement is true using rational approximations, let's evaluate each expression.
-
\( \sqrt{81} < 9 \)
- \( \sqrt{81} = 9 \)
- This statement is false since \( 9 = 9 \).
-
\( \sqrt{71} > \sqrt{61} \)
- We know that \( 71 > 61 \), and since the square root function is increasing for positive numbers, \( \sqrt{71} > \sqrt{61} \) is true.
-
\( \sqrt{81} > 9 \)
- Again, \( \sqrt{81} = 9 \), so this statement is false since \( 9 = 9 \).
-
\( \sqrt{71} < \sqrt{61} \)
- This statement is false, as established in the second point.
Based on the evaluations above, the true statement among the given options is:
\( \sqrt{71} > \sqrt{61} \).