Topic: Rational Equations and Applications
Subtopic: Applications - Work & Motion
Overview
Today we are going to apply our knowledge of solving rational equations to two types of word problems. We cover work problems where people or machines are working and motion problems where people or machines are moving. Organizing the information into a chart is recommended. Once you are able to form an equation it will likely be rational in nature solvable by the LCD or cross-products method we recently studied.
Objectives
By the end of this topic you should know and be prepared to be tested on:
- 9.3.1 Solve word problems involving proportions
- 9.3.2 Solve word problems involving work (e.g., painters, plumbers, copy machines)
- 9.3.3 Solve word problems involving motion (e.g., cars, bikes, trains, planes, boats)
- 9.3.4 Solve motion problems involving currents (e.g., headwinds, river currents)
Terminology
Define: rate, memorize the distance=rate*time formula D=RT
Text Notes
Text:
Intro & Inter Algebra for CS 3ed by Blitzer, sect. 7.7-7.8
- This section covers several types of word problems. Concentrate mostly on the work and motion types. Also be prepared to be tested on the proportion types which are readily solved by the cross-products method.
- pg 522-524 You can SKIP all the "similar triangles" problems. This material is covered in a pre-calculus class.
- SKIP section 7.8 completely.
Supplementary Resources
Translating and solving word problems is often a sticking point for students, but if you keep an optimistic attitude, take one step at a time, and read the problem carefully, you can do it! Here are some useful free resources:
- Mildred Johnson wrote an excellent little book that covers solving several different types of word problems in a manner similar to that we do here. Most of it is available free online in Google books How to Solve Word Problems in Algebra, 2nd ed. Start at page 19 for motion problems and at page 123 for work problems.
- OnlineMathLearning.com covers examples of Motion Problems and Work Problems.
- PurpleMath.com is always recommended! See Motion Problems and Work Problems.