| Rational Expressions | 
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 A Rational Expression is an algebraic fraction which has polynomials in both the numerator and denominator.  | 
Rational Expressions can be added and subtracted just like regular fractions.
| Unlike Denominators | 
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 Fractions with different values in their denominators have unlike denominators.  | 
To make the denominators equal, we need to find their Least Common Multiple(LCM).
 
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Figure 1. | 
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First, we need to find the LCM of the two fractions above:
 
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Figure 2. | 
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Now we need to make both fractions have "2x" in their denominator, then we can subtract them:
 
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Figure 3. | 
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