Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Select all the numbers that are rational.\newlineMulti-select Choices:\newline(A)18\sqrt{18}\newline(B)0.81-0.81\newline(C)0.180.\overline{18}\newline(D)81-\sqrt{81}\newline(E)81\frac{\sqrt{8}}{\sqrt{1}}

Full solution

Q. Select all the numbers that are rational.\newlineMulti-select Choices:\newline(A)18\sqrt{18}\newline(B)0.81-0.81\newline(C)0.180.\overline{18}\newline(D)81-\sqrt{81}\newline(E)81\frac{\sqrt{8}}{\sqrt{1}}
  1. Analyze 18\sqrt{18}: Step 11: Analyze (A) 18\sqrt{18}.18=9×2=3×2\sqrt{18} = \sqrt{9\times2} = 3\times\sqrt{2}.2\sqrt{2} is known to be irrational; therefore, 3×23\times\sqrt{2} is also irrational.
  2. Analyze 0.81-0.81: Step 22: Analyze (B) 0.81-0.81.\newline0.81-0.81 is a decimal that terminates.\newlineTerminating decimals are rational numbers.
  3. Analyze 0.180.\overline{18}: Step 33: Analyze (C) 0.180.\overline{18}. 0.180.\overline{18} represents the repeating decimal 0.1818180.181818\ldots Repeating decimals are rational numbers.
  4. Analyze 81-\sqrt{81}: Step 44: Analyze (D) 81-\sqrt{81}.81=9.-\sqrt{81} = -9.9-9 is a whole number, and all whole numbers are rational.
  5. Analyze 81\sqrt{\frac{8}{1}}: Step 55: Analyze (E) 81\sqrt{\frac{8}{1}}.81=81=8\sqrt{\frac{8}{1}} = \frac{\sqrt{8}}{1} = \sqrt{8}.8=42=22\sqrt{8} = \sqrt{4\cdot2} = 2\cdot\sqrt{2}.Since 2\sqrt{2} is irrational, 222\cdot\sqrt{2} is also irrational.

More problems from Checkpoint: Rational and irrational numbers