Use a Computer Algebra System (CAS) to Evaluate ExpressionsEvaluate 2x3 when x1.Turn on the TI-89 calculator. Press ÍHOMEto display the CAS home screen. Clear the calculator’s memory. It is wise to do this each time you use the CAS.• Press n[F6] to display the Clean Upmenu.• Select 2:NewProb.• Press e.Enter the expression and the value of x:• Press 2 ÍX+ 3 Í|ÍX=1.• Press e. 13.Evaluate.a)2x1 when x3b)4x2 when x1c)3y5 when y114.Use a CAS to check your answers inquestion 1. Hint: first substitute x2, and then substitute y3 into the resultingexpression.This key means “such that”.

8MHR• Chapter 1Connect English With Mathematicsand Graphing LinesThe key to solving many problems inmathematics is the ability to read andunderstand the words. Then, you cantranslate the words into mathematicsso that you can use one of the methodsyou know to solve the problem. In thissection, you will look at ways to helpyou move from words to equationsusing mathematical symbols in orderto find a solution to the problem.placemat or sheet of paperToolsInvestigateHow do you translate between words and algebra?Work in a group of four. Put your desks together sothat you have a placemat in front of you and eachof you has a section to write on.1.In the centre of the placemat, write the equation4x6 22.2.On your section of the placemat, write as many word sentences todescribe the equation in the centre of the placemat as you can thinkof in 5 min.3.At the end of 5 min, see how many different sentences you haveamong the members of your group.4.Compare with the other groups. How many different ways did yourclass find?5.Turn the placemat over. In the centre, write the expression x1.6.Take a few minutes to write phrases that can be represented by this expression.7.Compare among the members of your group. Then, check with other groups to see if they have any different phrases.8.Spend a few minutes talking about what words you used.9.Reflect Make a list of all the words you can use to represent each ofthe four operations: addition, subtraction, multiplication, and division.12

Example 1 Translate Words Into Algebraa)Write the following phrase as a mathematical expression:the value five increased by a numberb)Write the following sentence as a mathematical equation.c)Translate the following sentence into an equation, using twovariables. Mario’s daily earnings are $80 plus 12% commission onhis sales.Solutiona)Consider the parts of the phrase.• “the value five” means the number 5• “increased by” means add or the symbol • “a number” means an unknown number, so choose a variablesuch as nto represent the numberThe phrase can be represented by the mathematical expression 5 n.