Mathematics » Rational Expressions and Equations » Add and Subtract Rational Expressions with a Common Denominator

# Add and Subtract Rational Expressions Summary I

## Key Concepts

• If $$p,q,\phantom{\rule{0.2em}{0ex}}\text{and}\phantom{\rule{0.2em}{0ex}}r$$ are polynomials where $$r\ne 0$$, then

$$\frac{p}{r}+\frac{q}{r}=\frac{p+q}{r}$$

• To add rational expressions with a common denominator, add the numerators and place the sum over the common denominator.
• Rational Expression Subtraction
• If $$p,q,\phantom{\rule{0.2em}{0ex}}\text{and}\phantom{\rule{0.2em}{0ex}}r$$ are polynomials where $$r\ne 0$$, then

$$\frac{p}{r}-\frac{q}{r}=\frac{p-q}{r}$$

• To subtract rational expressions, subtract the numerators and place the difference over the common denominator.

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