INSTRUCTORSCarleen EatonGrant Fraser

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### Rational Expressions

• A rational expression is a fraction whose numerator and denominator are polynomials.

• Any values of the variable that make the denominator equal to zero produce an undefined expression. So these values must be excluded when we consider the rational expression.

• To simplify a rational expression, factor the numerator and denominator completely. Then cancel the common factors.

• If two factors in the numerator and denominator look almost the same, factor –1 out of either of the factors and see if you get two identical factors.

• Excluded values are always determined using the original expression, not the simplified one.

## Rational Expressions

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