Expressions With Substitution King/Halling Algebra 2011-2012

AIM When we want to evaluate expressions using specific values, how can we replace variables with the numbers they equal? Topic: Expressions & Substitution

DO NOW Take out your completed foldable and your worksheets from yesterday. Make sure you know what homework you are missing when we come around to check these assignments. Complete the following using PEMDAS FLTR: [10(6 – 4)2 – (16 ÷ 4)] + 52

[10(6 – 4)2 – (16 ÷ 4)] + 52

Evaluating Expressions When evaluating expressions, sometimes you will find that they include variables Example: 10(a – 3) x (b + 4) Often times they will ask you to evaluate these expressions using given values for these variables. Let’s try it!!

10(a – 3) x (b + 4) Evaluate this expression when a = 4 and b = 6. In order to complete this, we simply substitute the values of the variables into the expression SO… 10(a – 3) x (b + 4)  10(4 – 3) x (6 + 4) Now solve it!  10(1) x (6 + 4) 10(1) x (10) 10 x 10 100

10(a – 3) x (b + 4) The answer will change when we change the value of the variables we try. Let’s use a = 6 and b = 4 10(a – 3) x (b + 4)  10(6 – 3) x (4 + 4) 10(3) x (4 + 4) 10(3) x (8) 30 x 8 240

Evaluate 6(7 – x)2 + y for x=4 and y=9 Evaluate 2(m + 9) – 52 x n for m=12 and n=4 Evaluate [7(5 – a) + b2 ÷ c for a=4,b=9,& c=4

Using the Calculator To check your answers or complete these problems in a different way, you can use your calculator The Store function of the calculator is one of the most useful buttons when taking the Regents

Steps for the Calculator Type the value of the variable into the calculator Hit the STO> button directly above ON Hit ALPHA and the variable you want to use Type in the problem and hit ENTER

Solve the equation using substitution to check your answer! 11(a – 3) ÷ b2 when a=11 and b = 2 Hit 9 then STO> and ALPHA “A” Hit 2 then STO> and ALPHA “B” Type in the equation 11(A – 3) ÷ B2 Hit ENTER The answer is 22 Solve the equation using substitution to check your answer!

Example 2: Evaluate [10(a + 3) – b2] when a=5 and b=4

Example 3: Evaluate [33 – 10(x – 1)]y when x=4 and y=2

More Practice Evaluate 6(7 – x)2 + y for x=4 and y=9 Evaluate 2(m + 9) – 52 x n for m=12 and n=4

Exit Ticket Evaluate the following expressions using whatever method you prefer and the values provided for the variables: (a2 + b2) – 10 when a=6 and b=7 a2 + (b2 – 10) when a=6 and b=7