Lesson 4

1. Lesson 4

1.7. Explore 3

Mathematics 20-1 Module 6

Module 6: Rational Expressions

Using Cross Multiplication

A short-cut strategy for solving rational equations of the form is to solve the equivalent equation ad = bc. If you are not convinced this shortcut works, choose two fractions that you know are equivalent and try the short cut.

For example, is the same as 2(6) = 3(4)?

Try this short cut on the rational equation in Try This 2.

When you have seen that the short cut works, figure out why it works. If you can figure out how the rational equation is equivalent to ad = bc, you will have figured out why the short cut works.

Work through Rational Equations to practise applying the steps in solving rational equations. Select the tutorial icon at the top of the window. Beginning with Defining Rational Equations, work through each part of the tutorial. You will be guided through each step of the process. As you work through the mini-example, focus on the following questions:

This is a play button that opens Rational Equations.

How do you multiply the LCD against each side of the equation?

Why do you end up with a quadratic equation after multiplying each side of the equation by the LCD? Will this happen every time?

Self-Check 1

This is a play button that opens Solving Rational Equations Self-Check.

Complete Solving Rational Equations Self-Check.