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Subtracting Fractions with Unlike Denominators

How do we ensure the fractions have the same denominator?

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We ensure the fractions have the same denominator by multiplying each fraction by an appropriate form of 1 that converts its denominator to the desired common denominator.

How do we subtract two fractions?

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To subtract two fractions, we need to get common denominators. A simple way to find a common denominator is to multiply the two denominators.

What is a common denominator?

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A common denominator is a number that both denominators can divide into without leaving a remainder.

How do we get the same denominator for two fractions?

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To get the same denominator, we multiply the first fraction by the denominator of the second fraction over itself, and the second fraction by the denominator of the first fraction over itself.

Does multiplying by the denominator over itself change the value of the fraction?

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No, multiplying by the denominator over itself does not change the value of the fraction, as it is equivalent to multiplying by 1.

After finding a common denominator, what do we do next?

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After finding a common denominator, we subtract the numerators of the two fractions.

Can you provide an example of subtracting two fractions with different denominators?

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Sure, let's subtract 7/8 by 3/5. The common denominator is 8 * 5, which is 40. We then multiply the first fraction by 5/5 and the second fraction by 8/8 to get the same denominator, then subtract the numerators to get 11/40.

What is the result of subtracting 7/8 by 3/5?

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The result of subtracting 7/8 by 3/5 is 11/40.

How do we simplify the fraction after subtraction?

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After subtraction, if the fraction is not in its simplest form, we can simplify it by dividing both the numerator and the denominator by their greatest common divisor.

What is the process to simplify a fraction?

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To simplify a fraction, we find the greatest common divisor of the numerator and the denominator, and then divide both by that number.

What is the result of subtracting 4/9 by 1/7?

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The result of subtracting 4/9 by 1/7 is 19/63.

Can you give another example of subtracting two fractions?

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Certainly, let's subtract 4/9 by 1/7. The common denominator is 9 * 7, which is 63. We then multiply the first fraction by 7/7 and the second fraction by 9/9 to get the same denominator, then subtract the numerators to get 19/63.

What is the greatest common divisor of 11 and 40?

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The greatest common divisor of 11 and 40 is 1, as 11 is a prime number and does not divide evenly into 40.

What is the greatest common divisor of 19 and 63?

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The greatest common divisor of 19 and 63 is 1, as 19 is a prime number and does not divide evenly into 63.

Why is it important to have the same denominator when subtracting fractions?

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It is important to have the same denominator when subtracting fractions because it allows us to directly subtract the numerators without having to convert anything.

Can you explain the concept of least common denominator?

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The least common denominator is the smallest common multiple of the denominators of the fractions being subtracted. It is the smallest number into which both denominators can divide evenly.

Is it always necessary to find the least common denominator when subtracting fractions?

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No, it is not always necessary to find the least common denominator. Any common denominator will work, but using the least common denominator can simplify the process and the result.

How do we ensure the fractions have the same denominator?

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We ensure the fractions have the same denominator by multiplying each fraction by an appropriate form of 1 that converts its denominator to the desired common denominator.

How do we subtract two fractions?

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To subtract two fractions, we need to get common denominators. A simple way to find a common denominator is to multiply the two denominators.

    flashcard: How to Subtract Fractions with Different Denominators: Easy Steps