Solutions

Solving Using Cross Products

A rational equation that contains two terms, a proportion, is easily solved by the method of cross products or cross multiplication. This turns a rational equation into a polynomial equation.

Example 1 Solve.

Frac1

Step 1. Use cross-multiplication to turn the rational equation into a polynomial equation.

Frac2

Step 2. Solve the equation.

Frac3

Step 3. Check for extraneous solutions.

The original equation had no excluded values, so Frac4 is not an extraneous solution.

*Remember: you can always check your answers by plugging the solutions into the original equation.