Example

Simplifying 13+161213\frac{\frac{1}{3}+\frac{1}{6}}{\frac{1}{2}-\frac{1}{3}} Using the LCD

Simplify the complex rational expression using the LCD method:

13+161213\frac{\frac{1}{3}+\frac{1}{6}}{\frac{1}{2}-\frac{1}{3}}

Step 1 — Find the LCD of all fractions in the expression. The four inner fractions have denominators 33, 66, 22, and 33. The LCD of these numbers is 66.

Step 2 — Multiply the numerator and denominator by 66. Distribute 66 to each term in the numerator and denominator:

613+616612613\frac{6 \cdot \frac{1}{3} + 6 \cdot \frac{1}{6}}{6 \cdot \frac{1}{2} - 6 \cdot \frac{1}{3}}

Step 3 — Simplify. Evaluate each product: 613=26 \cdot \frac{1}{3} = 2, 616=16 \cdot \frac{1}{6} = 1, 612=36 \cdot \frac{1}{2} = 3, and 613=26 \cdot \frac{1}{3} = 2:

2+132=31=3\frac{2 + 1}{3 - 2} = \frac{3}{1} = 3

The result is 33 — the same answer obtained when this expression is simplified by the division method. The LCD approach reaches the answer more directly: instead of separately simplifying the numerator and denominator into single fractions before dividing, multiplying every term by the LCD of 66 clears all fractions in a single step.

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Updated 2026-04-30

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