Practice Irrational Numbers in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

An irrational number is a real number that cannot be expressed as a ratio of two integers pq\frac{p}{q}; its decimal expansion goes on forever without repeating any fixed block of digits.

Ο€\pi and 2\sqrt{2} go on forever without any patternβ€”you can't write them as a fraction.

Showing a random 20 of 50 problems.

Example 1

challenge
Prove that 2\sqrt{2} is irrational (outline the contradiction).

Example 2

easy
Is 2\sqrt{2} rational or irrational?

Example 3

hard
Is the set of irrationals closed under addition?

Example 4

easy
Is 25\sqrt{25} rational or irrational?

Example 5

medium
Classify each: 0.04\sqrt{0.04}, 0.5\sqrt{0.5}.

Example 6

medium
Order from least to greatest: 8,3,Ο€\sqrt{8}, 3, \pi.

Example 7

medium
Rationalize and classify 12\frac{1}{\sqrt{2}}.

Example 8

medium
Order from least to greatest: 2,Β 1.5,Β 3\sqrt{2},\ 1.5,\ \sqrt{3}.

Example 9

medium
Is 182\frac{\sqrt{18}}{\sqrt{2}} rational or irrational?

Example 10

easy
Is 11\sqrt{11} rational or irrational?

Example 11

medium
Give an example of an irrational number between 1.11.1 and 1.21.2.

Example 12

medium
Simplify 72\sqrt{72} and classify it.

Example 13

challenge
Show that 2+3\sqrt{2} + \sqrt{3} is a root of a polynomial with integer coefficients; what is its minimal polynomial?

Example 14

easy
Is 49+3\sqrt{49} + \sqrt{3} rational or irrational? Explain.

Example 15

easy
Between which two consecutive integers does 19\sqrt{19} lie?

Example 16

medium
Show that 2\sqrt{2} lies between 1.41.4 and 1.51.5, then estimate it to one decimal place.

Example 17

medium
Prove that 3\sqrt{3} is irrational by contradiction.

Example 18

medium
Give an example of two irrational numbers whose sum is rational.

Example 19

medium
Is 2β‹…Ο€\sqrt{2} \cdot \pi rational or irrational?

Example 20

medium
Simplify 50\sqrt{50} and state whether it is rational.