Operations with RationalsA series of free Intermediate Algebra Video Lessons from Brightstorm online Algebra series.
Definition and Domain of a Rational Expression We have rational expressions whenever we have a fraction that has a polynomial in the numerator and/or in the denominator. An excluded value in the function is any value of the variable that would make the denominator equal to zero. To find the domain, list all the values of the variable that, when substituted, would result in a zero in the denominator.
Multiplying and Dividing Rational Expressions Dividing rational expressions is basically two simplifying problems put together. When dividing rationals, we factor both numerators and denominators and identify equivalents of one to cancel. After identifying these equivalents, we take the reciprocal of the second fraction and divide. Multiplying rational expressions is the same as dividing rationals, except that we do not take the reciprocal of the second fraction.
Adding and Subtracting Rational Expressions Adding and subtracting rational expressions is similar to adding fractions. When adding and subtracting rational expressions, we find a common denominator and then add the numerators. To find a common denominator, factor each first. This strategy is especially important when the denominators are trinomials.
Simplifying Complex Fractions Simplifying rational expressions combines everything learned about factoring common factors and polynomials. When simplifying complex fractions, factor the numerator and denominator into terms multiplying each other and look for equivalents of one (something divided by itself). Include parenthesis around any expression with a "+" or "-" and if all terms cancel in the numerator, there is still a one there.
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