Presentation on theme: "1.1 What you should learn Why you should learn it Variables in Algebra"— Presentation transcript:
1 1.1 What you should learn Why you should learn it Variables in Algebra GOAL1Evaluate a variable expression.GOAL2Write a variable expression that models a real-life situation.Why you should learn itTo express real-life number relationships.
2 1.1 Variables in Algebra 1 GOAL EVALUATING VARIABLE EXPRESSIONS VOCABULARYvariablevaluesvariable expressionevaluating an expression
3 To evaluate a variable expression, follow these three steps: Write the variable expression.Substitute values for variables.Simplify the numerical expression.EXAMPLE 1
4 Extra Example 1Evaluate each expression when y = 3. Click for solutions.1. 4y y yEXAMPLE 2
5 Extra Example 2Find the average speed, of a car that traveled 89 miles in 2 hours.Solution:average speed44.5 mi/hEXAMPLE 3
6 Extra Example 3Find the perimeter, a + b + c, of the triangle. The dimensions are in centimeters.Click to see the solution.a = 1b = 1.75c = 2.25Perimeter = a + b + c==5 cm
7 Checkpoint1. Find the average speed of a car that travels 225 miles in 4.5 hours.50 mi/hFind the perimeter of the triangle. The dimensions are in inches. Click for the answers.c = 6.7a = 8b = 8EXAMPLE 422.7 in
8 convert the interest rate Extra Example 4Find the simple interest, Prt, you will earn in two years on a deposit of $870 at a rate of 5% per year.Click for the solution.Simple interest = Prt=Did you remember toconvert the interest rateto a decimal number?These unitscancel.$87
9 1.1 Variables in Algebra 2 GOAL MODELING A REAL-LIFE SITUATION VOCABULARYUnit AnalysisVerbal ModelEXAMPLE 5
10 Extra Example 5You plan to ride your bicycle to school and back at an average rate of 6 miles per hour for a distance of 10.5 miles. How long will it take you? Click to see the solution.VERBALMODELLABELSALGEBRAIC MODELTime=Time = tDistance = 10.5 milesRate = 6 mi/h1.75 hours
11 Checkpoint1. Find the simple interest you will earn after one half of a year with a deposit of $1250 at a rate of 6% per year.$37.50Your parents drive to the grocery store 9 miles away at 12:30 p.m. and return at 2:00 p.m. If the grocery shopping took 45 minutes, what was the average speed of their car?Click for the answers.24 mi/h
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