 # ALGEBRA LESSON 2 EVALUATING EXPRESSIONS AND CHECKING.

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ALGEBRA LESSON 2 EVALUATING EXPRESSIONS AND CHECKING

Evaluating Expressions  Given an algebraic expression, you will plug given numbers in for the variables and perform the operations.  Example: Find the value of x + 3 if x = 7 In this case, you will replace the x with 7 7 + 3 = 10 REMEMBER TO FOLLOW ORDER OF OPERATIONS FOR THOSE PROBLEMS WITH MORE THAN ONE OPERATION.

MORE EXAMPLES  Evaluate the following if a = 7  3a  a + 9  12 – a  3a + 4

MORE EXAMPLES  Evaluate the following if x = 3  4x  2x – 5  9 – 2x  5x + 2  Evaluate the following if y = -5  y – 7  9 – y  3y + 6  35 – 6y

MORE EXAMPLES  Evaluate the following if a = 2 and b = -3  3a + b  3b + a  2b – 2a  5ab  Evaluate the following if x = 9, y = -2, and z = 3  xyz  2x – z  -2y – z  x – 3y

CHECKING ANSWERS FOR ALGEBRAIC EQUATIONS  When we start solving equations (tomorrow), you can use what we learned today to CHECK to see if your answer is correct.  Simply plug the answer you received into the equation that you started with to see if you get the same result of the original problem  Ex. 3x = 27you get an answer of 9  Check this by plugging 9 in for x….do you get 27?

More Examples (Check)

HOMEWORK  EVALUATING EXPRESSIONS WORKSHEET