It often happens that we have to compare fractions with different numerators and different denominators.

For example, compare fractions 5/2 and 2/3. To answer the question of which of these fractions is larger or smaller, you must reduce them to the same (common) denominator. Then you can easily determine which fraction is larger or smaller.

Let's reduce fractions 5/2 and 2/3 to the same (common) denominator. Find the least common multiple (LCM) of the denominators of both fractions. The LCM of the denominators of fractions 5/2 and 2/3 is 6.

Now find the additional multipliers for each fraction. Divide the LCM by the denominator of the first fraction 5/2. LCM is 6, and the denominator of the first fraction is 2. Divide 6 by 2, and we get an additional factor 3. Write it over the first fraction:

1631

Now find the second additional factor. Divide the LCM by the denominator of the second fraction 2/3. LCM is 6, and the denominator of the second fraction is 3. Dividing 6 by 3, we get an additional multiplier of 2. Write it over the second fraction:

1632

Multiply the fractions by their additional multipliers:

1633

We came to the conclusion that fractions with different denominators turned into fractions with the same denominators. And we already know how to compare such fractions. Of two fractions with the same denominators, the one with the larger numerator is larger:

1634

The rule is a rule, but we'll try to figure out why 1636 is bigger than 1637. To do this, we highlight the whole part in the fraction 1636. In the fraction 1637, we don't need to isolate anything, because the fraction is proper.

After singling out the whole part of the fraction , we obtain the following expression:

After isolating the whole part in the fraction 1636, we get the following expression:

1638

Now it's easy to see why 1636 is bigger than 1637. Let's draw these fractions as pizzas:

1635

2 whole pizzas and 1639 pizzas, more than 1637 pizzas.


Exercises

Task 1. Compare fractions:
Solution:
Task 2. Compare fractions:
Solution:
Task 3. Compare fractions:
Solution:

Video lesson

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