Phrase or TermDefinitionExample A variableThe letter which stands for a number that can change. ‘x’ in 2x-6 is a variable. Its value could be 4, or -6, or any other number. A functionThe relationship between two variables. y = 2x is a relationship between two variables (x and y). In this case, the function says “y is always twice as much as x”. University Prep Math Steve Greer hrsbstaff.ednet.ns.ca/sgreer Phrase or TermDefinitionExample A variableThe letter which stands for a number that can change. ‘x’ in 2x-6 is a variable. Its value could be 4, or -6, or any other number. Phrase or TermDefinitionExamplePhrase or TermDefinitionExample A variableThe letter which stands for a number that can change. ‘x’ in 2x-6 is a variable. Its value could be 4, or -6, or any other number. A functionThe relationship between two variables. y = 2x is a relationship between two variables (x and y). In this case, the function says “y is always twice as much as x”. Evaluating an expressionFinding out what the value of the expression is when you know the value of the variable. Evaluate: 4x-1 when x = 3. We plug in a 3 wherever we see an ‘x’ and follow the order of operations.

Order of Operations: When to do what RACKETSRACKETS XPONENTSXPONENTS IVISIONIVISION ULTIPLACTIONULTIPLACTION D DDITIONDDITION UBTRACTIONUBTRACTION

“Evaluating an Expression” examples Evaluate the following expressions given the value of the variable stated. 1.7x-3 if x = (x-2) if x = r -7t -6 if r = 2 and t = 14. 3t 2 +5t -9 if t = 2 5.3x(x-2) + x/2 if x = 4 6. if j = 3 Answers:

Phrase or TermDefinitionExample Solving an equation or finding the roots. Finding out what the value of the variable is when you know what the expression equals. This is the opposite as evaluating the expression. Root – the value of the variable that makes the equation true. Solve for ‘x’. 3x-4 = 8 We will “undo” BEDMAS Find the root of each equation. 1) 5(x-4) = 102) 8w – 2 = -42 3) ½ (g+1) = 6 4) 3x + 6 = 9x – 4 5) 6) Answers: 1)6 2) -5 3) 11 4) 10/6 = ) 26 6) -3

Where do these functions come from? We have worked with a few expressions and a few equations but what do they mean? Let’s look out how our every day lives use functions all the time!

Cell Phone Bill – A function What are two variables involved in cell phone use? We can find a relationship between the cost of the bill and the time of usage. Which variable depends on the other? Let’s say that it costs 20 cents per minute and that you are always charged a monthly fee of $7.00. Questions: 1) What is the function and its graph? 2) If you talked for 45 minutes, what will your bill be? 3) If your bill is $37.40, how many minutes were you on the phone?