Practice Quantifiers in Math

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

Quick Recap

Symbols specifying the scope of a predicate: ∀ (for all, universal) and ∃ (there exists, existential).

∀ means 'for all' (everyone). ∃ means 'there exists' (at least one).

Showing a random 20 of 50 problems.

Example 1

easy
Fill in: The negation of ∃x, P(x) is ____.

Example 2

easy
True or false over Z: ∀n, 2n is even.

Example 3

medium
Fill in: ¬(∀x, P(x)∧Q(x)) is equivalent to ∃x, □. Fill the □.

Example 4

challenge
Express 'there is exactly one x with P(x)' using ∃, ∀, and equality.

Example 5

easy
Is '∀x∈R, x2≥0' true or false?

Example 6

easy
Translate into symbols and determine the truth value: (a) 'Every natural number is positive.', (b) 'There exists a real number x such that x2=2.'

Example 7

medium
Translate: 'The function f is surjective from A to B' using quantifiers.

Example 8

medium
Disprove '∀n∈N, n2≥2n' by giving a counterexample or show it is true.

Example 9

medium
Translate 'every integer is even or odd' and write its negation.

Example 10

easy
Write in words: (a) ∀x∈Z,  x+0=x, (b) ∃x∈N,  x<5.

Example 11

medium
Rewrite 'no real number satisfies x2<0' with a quantifier, then give the equivalent universal form.

Example 12

challenge
Translate uniqueness '∃!x, P(x)' using only ∃,∀,→,=.

Example 13

medium
Translate, then determine truth over R: 'For every positive real x there is a positive real y with y<x.'

Example 14

hard
Over R, decide and justify: '∃x, ∀y, x+y>y.'

Example 15

easy
Translate 'every prime greater than 2 is odd' into quantifier notation (let P(x) = 'x is prime', x>2).

Example 16

medium
Determine the truth value of each and write its negation: (a) ∀x∈R,  x>0, (b) ∃x∈Z,  x2=3.

Example 17

easy
What does the symbol ∀ mean?

Example 18

hard
Translate 'there is no largest integer' two ways: (a) with ¬∃, (b) with ∀∃.

Example 19

easy
Fill in: The negation of ∀x, P(x) is ____.

Example 20

easy
Write the negation of 'Every car in the lot is red' in plain English.