ALGEBRA LESSON 2ALGEBRA LESSON 2

EVALUATING EXPRESSIONS AND EVALUATING EXPRESSIONS AND CHECKINGCHECKING

Evaluating ExpressionsEvaluating Expressions

Given an algebraic expression, you will plug Given an algebraic expression, you will plug given numbers in for the variables and perform given numbers in for the variables and perform the operations.the operations.

Example: Find the value of x + 3 if x = 7Example: Find the value of x + 3 if x = 7In this case, you will replace the x with 7In this case, you will replace the x with 7

7 + 3 = 7 + 3 = 1010

REMEMBER TO FOLLOW ORDER REMEMBER TO FOLLOW ORDER OF OPERATIONS FOR THOSE OF OPERATIONS FOR THOSE PROBLEMS WITH MORE THAN PROBLEMS WITH MORE THAN ONE OPERATION.ONE OPERATION.

MORE EXAMPLESMORE EXAMPLES

Evaluate the Evaluate the following if a = 7following if a = 7 3a3a

a + 9a + 9

12 – a12 – a

3a + 43a + 4

MORE EXAMPLESMORE EXAMPLES

Evaluate the Evaluate the following if x = 3following if x = 3 4x4x

2x – 52x – 5

9 – 2x9 – 2x

5x + 25x + 2

Evaluate the Evaluate the following if y = -5following if y = -5 y – 7y – 7

9 – y9 – y

3y + 63y + 6

35 – 6y35 – 6y

MORE EXAMPLESMORE EXAMPLES

Evaluate the Evaluate the following if a = 2 and following if a = 2 and b = -3b = -3 3a + b3a + b

3b + a3b + a

2b – 2a2b – 2a

5ab5ab

Evaluate the Evaluate the following if x = 9, following if x = 9, y = -2, and z = 3y = -2, and z = 3 xyzxyz

2x – z2x – z

-2y – z-2y – z

x – 3yx – 3y

CHECKING ANSWERS FOR CHECKING ANSWERS FOR ALGEBRAIC EQUATIONSALGEBRAIC EQUATIONS

When we start solving equations (tomorrow), When we start solving equations (tomorrow), you can use what we learned today to CHECK you can use what we learned today to CHECK to see if your answer is correct. to see if your answer is correct.

Simply plug the answer you received into the Simply plug the answer you received into the equation that you started with to see if you get equation that you started with to see if you get the same result of the original problemthe same result of the original problem

Ex. 3x = 27Ex. 3x = 27 you get an answer of 9you get an answer of 9 Check this by plugging 9 in for x….do you get Check this by plugging 9 in for x….do you get

27?27?

More Examples (Check)More Examples (Check)

HOMEWORKHOMEWORK

EVALUATING EXPRESSIONS EVALUATING EXPRESSIONS WORKSHEETWORKSHEET