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Rational numbers

Source: licencja: CC 0.

Liczby wymierne

Learning objectives

  • Writing the number in the form of reduced fraction.

  • Identifying natural numbers, integers, rational numbers, multiplicative reverses, additive inverses and marking them on the number line.

Learning effect

  • You write the number in the form of reduced fraction.

  • You identify natural numbers, integers, rational numbers, multiplicative inverses, additive inverses and marking them on the number line.

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nagranie abstraktu

Discussion.

  • What number is called rational? Look for information in available sources of knowledge.

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nagranie abstraktu
Definition of the rational number
Definition: Definition of the rational number

A rational number is a number that can be written in the form of a reduced fraction ab, where a and b are integersintegersintegers and b0.

Rational numbersrational numbersRational numbers are natural numbersnatural numbersnatural numbers, integersintegersintegers and fractionsfractionsfractions.

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nagranie abstraktu

Chain of associations.

On a big cardboard draw a chain consisting of empty links. Fill in the links with names of number sets and their most important properties.

Use obtained information in exercises.

Task 1
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nagranie abstraktu

Prove that the following numbers are rational.

a) -4,7

b) 547

c) 0,(8)

d) -3,(9)

Task 2
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nagranie abstraktu

Mark the following numbers on the number line. Remember about choosing the right unit.

a) 14;1,5

b) -4,2; -2,8

c) 27;87

d) 74;2,75

Task 3
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nagranie abstraktu

Read what numbers correspond to points marked on the number line.

Your task is to place a point on the number line so that it has the given coordinate.

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Geogebra aplet - liczby na osi liczbowej. Galeria z opisami alternatywnymi poniżej.
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

What rational numbersrational numbersrational numbers are called additive inversesadditive inversesadditive inverses and what are multiplicative inversesmultiplicative inversesmultiplicative inverses? Make theories and verify them using available sources of information, for example the Internet.

Conclusions:

  • The multiplicative inverse for the number a, for a0 is the number 1a.

  • Inverses are number that are located on the opposite sides of 0 on the number line and whose distance from 0 is the same.

Use obtained information by doing exercises.

Task 4
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nagranie abstraktu

Find the multiplicative inverse for each number.

2,3;317;5,625;0,(4);4211

Task 5
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nagranie abstraktu

From the following pairs choose those that are pairs of additive inversesadditive inversesadditive inverses and those that are pairs of multiplicative inversesmultiplicative inversesmultiplicative inverses.

43and34

15and5

2,8and8,2

0,625and85

127and172

2,2and511

4,4and225

4,5and92

Task 6

An extra task:

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nagranie abstraktu

Identify all integersintegersintegers whose distance from zero on the number line is smaller than 4,(9).

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. A number that has a repeating decimal form is a rational number., 2. Each integer is a natural number., 3. Each rational number is an integer., 4. Each rational number can be written down as a common reduced fraction.
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Exercise 2
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. The additive inverse of an integer is also an integer., 2. The sum of any number and its additive inverse is equal to 0., 3. Each natural number has its multiplicative inverse., 4. The product of any number different than zero and its multiplicative inverse is equal to 1.
Exercise 3

Prove that the number 2,(32) is a rational number. Present the solution in English.

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Exercise 4
Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. liczby naturalne - natural numbers, 2. liczby całkowite - integers, 3. liczby wymierne - rational numbers, 4. ułamki - fractions, 5. liczby odwrotne - additive inverses, 6. liczby przeciwne - multiplicative inverses
zadanie
Source: GroMar, licencja: CC BY 3.0.
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

additive inverses
additive inverses

liczby przeciwne

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wymowa w języku angielskim: additive inverses
fractions
fractions

ułamki

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wymowa w języku angielskim: fractions
integers
integers

liczby całkowite

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wymowa w języku angielskim: integers
multiplicative inverses
multiplicative inverses

liczby odwrotne

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wymowa w języku angielskim: multiplicative inverses
natural numbers
natural numbers

liczby naturalne

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wymowa w języku angielskim: natural numbers
rational numbers
rational numbers

liczby wymierne

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wymowa w języku angielskim: rational numbers

Keywords

additive inversesadditive inversesadditive inverses

integersintegersintegers

multiplicative inversesmultiplicative inversesmultiplicative inverses

natural numbersnatural numbersnatural numbers - to liczby: 0, 1, 2, 3, ...

rational numbersrational numbersrational numbers – liczby, które można przedstawić w postaci ułamka nieskracalnego ab, gdzie a i b są liczbami całkowitymi i b0