Reduce fractions to a common denominator Review 1

Reduce fractions to a common denominator

Review 1: 1)Write down 3 fractions in their simplest form with a denominator of 8. 2)Write down 3 fractions in their simplest form with a denominator of 9. 3)Simplify the following fractions:

Comparing fractions: 3 2 > 9 9 4< 5 7 7 3 4 5 6

3 4 5 6 We need a commom denominator to compare these fractions.

3 3× 3 9 = = 4 4× 3 12 So 3 5 < 4 6 5 5× 2 10 = = 6 6× 2 12

Find the LCD! Equivalent Common denominators Different denominators fractions

Finding the Least Common Multiple (LCM): 3, 4 6, 12 LCM =12 6, 9 LCM =18 3, 4, 8 LCM =24 5, 10, 20 LCM =20

Making equivalent fractions: × 4 × 3 × 2 12 6 12 × 3 × 4

Reduction of fractions to a common denominator Step 1: Find the LCD(LCM) Step 2: Write the equivalent fractions 12

Reduction of fractions to a common denominator Step 1: Find the LCD 12 Step 2: Write the equivalent fractions

Reduction of fractions to a common denominator Step 1: Find the LCD 24 Step 2: Write the equivalent fractions

⑵ ⑴ ( Improve： ？) ⑶ ( √ ) (× correct： Any common denominator could be used. But the Least Common Denominator(LCD) makes the computation easier. )

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Reduction of fractions to a common denominator

summary How to reduce fractions to a common denominator? Step 1: Find the LCD(LCM) Step 2: Write the equivalent fractions