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Summary of Fractions: Common Denominators

Mathematics

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Fractions: Common Denominators


INTRODUCTION

The Relevance of the Topic

  • Building mathematical foundations: Fractions are key pieces in Mathematics, like bricks that help build a house. Learning about common denominators is like learning to adjust the bricks so they fit perfectly.
  • Daily and routine use: Just as recipes need exact measurements for a delicious cake, common denominators are crucial for combining and comparing pieces of a whole accurately in everyday life.
  • Problem-solving ability: It's like having a screwdriver in the toolbox; adjusting fractions to have the same denominator enables solving various mathematical challenges, from adding to comparing fractions.

Contextualization

  • Link with previous concepts: We studied fractions as parts of a whole. Now we will make these parts "talk" to each other by changing their denominators, without changing their value.
  • Bridge to future skills: Mastering common denominators is like learning to swim in a pool before jumping into the ocean. It prepares for deeper waters of Mathematics, such as operations with fractions and even algebra.
  • Integration with other disciplines: Just like different instruments create a symphony, the ability to work with common denominators integrates Mathematics with areas such as science, cooking, and even economics, where fractions are applied.

THEORETICAL DEVELOPMENT

Components

  • Fraction: A division between two numbers, where the top one is called the numerator and shows how many parts we have, and the bottom one is the denominator, showing into how many parts the whole was divided.
  • Common denominator: A number that serves as a denominator for two or more fractions, allowing comparisons and operations between them.
  • Equivalent Fractions: Different fractions that represent the same value. They can be created by multiplying or dividing both the numerator and the denominator by the same number.

Key Terms

  • Numerator: The number above the fraction line, indicating the quantity of selected parts of the whole.
  • Denominator: The number below the fraction line, indicating into how many equal parts the whole was divided.
  • Least Common Multiple (LCM): The smallest number that is a multiple of two or more denominators.

Examples and Cases

  • Finding the Common Denominator: To combine (\frac{1}{4}) and (\frac{2}{3}), we find a common denominator. First, we list multiples of 4 (4, 8, 12, 16, ...) and 3 (3, 6, 9, 12, ...). The smallest multiple they share is 12, so 12 is the common denominator.
  • Creating Equivalent Fractions: To transform (\frac{1}{4}) and (\frac{2}{3}) to have denominator 12, we multiply the numerator and denominator of (\frac{1}{4}) by 3 (becoming (\frac{3}{12})) and of (\frac{2}{3}) by 4 (becoming (\frac{8}{12})).
  • Visualizing Equivalent Fractions: Imagine a cake cut into 4 equal parts ((\frac{1}{4})) and another cake cut into 3 equal parts ((\frac{2}{3})). If we cut the cakes again so that both have 12 equal parts, we still have the same amount of cake, but now we can easily compare, as we are using the same size of part – the slices are equivalent fractions.

DETAILED SUMMARY

Relevant Points

  • Identification of common denominators: The ability to see when fractions do not have the same denominator and the need to find one that serves both is the starting point. It's like identifying two screws of different sizes and knowing that we need an adjustable wrench to tighten them equally.
  • Use of the Least Common Multiple (LCM): We use the LCM to find a common denominator without unnecessarily increasing the size of the fractions. It's like finding the perfect shoe that fits two different feet, comfortably.
  • Transformation into equivalent fractions: We learn to transform fractions into equivalents with the common denominator, multiplying the numerator and denominator by the same number. Imagine a chameleon that can change color to match the environment, but it is still the same chameleon.
  • Visualization and manipulation: We use drawings and objects to visualize fractions and understand how different fractions represent the same amount. A puzzle may have pieces of different shapes, but when assembled, it always forms the same image.

Conclusions

  • Equivalent fractions do not change the amount: When we create equivalent fractions, the amount represented remains the same. It's like exchanging a R$10 note for two R$5 notes; the monetary value is the same, just the form changes.
  • Common denominators facilitate comparisons and operations: With a common denominator, we can easily add, subtract, or compare fractions. It's like lining up marbles in rows to see who has more, instead of trying to guess with them scattered.
  • Mathematics is flexible and adaptable: We learn that Mathematics allows us to change things in ways that help us solve problems, without losing the essence of the numbers or quantities we are working with.

Exercises

  1. Find the common denominator and transform the fractions (\frac{1}{6}) and (\frac{1}{8}) so that they have the same denominator. Then, draw a circle divided into these equivalent fractions.
  2. João has (\frac{3}{5}) of a pizza, and Maria has (\frac{2}{4}) of another pizza of the same size. What is the common denominator? Write the equivalent fractions so they can be compared.
  3. There are three ribbons of different sizes: one measures (\frac{3}{4}) m, another (\frac{5}{6}) m, and the third (\frac{7}{12}) m. All must be cut into equal pieces without any leftovers. What is the length of the pieces if all have the same common denominator?

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