Download Name - Jamestown Public Schools

Name________________
AT Algebra
Date______________
2.7 Evaluating Expressions
When evaluating an expression we must remember our order of operations:
PEMDAS
1)
2)
3)
4)
evaluate everything in parenthesis
exponents
multiply and divide left to right
add and subtract left to right
Practice:
6 x (-4) + 10
8 5  (4)
12
Example: Starting with 5 and
 then -3, multiply 6 times a starting number, then add 15,
divide this result by 3, and then subtract your answer from 80. Use your calculators:
5:
-3:
We can also put our work into a table:
Description
Starting value.
Multiply by 6.
Add 15.
Divide this result by 3.
Subtract your answer from 80.
Expression
x
We can even type in the algebraic expression into our calculators, take at look at how on
p136 in your text when you have some free time.
Investigation: Number Tricks
You will have two classes to finish the investigation and homework. You
Complete the investigation with your group. Read the directions carefully.
Try this trick: Each member of your group should think of a different number from 1 to 25.
My Number:__________
Add 9 to it.
Multiply the result by 3.
Subtract 6 from the current answer.
Divide this answer by 3.
Now subtract your original number.
Compare your results.
Step1: The brackets that look like { and } are in the text menu. The -> is the sto->.
Step2:
Step3:
Step4:
Description
Step5 and Step6:
Expression
Stage
Picture
1
n
2
n +1 +1 +1
3
n n +1 +1 +1 +1 +1 +1
4
n n +1 +1
5
n +1
6
+1
7
+1 +1 +1
Description
Expression
Pick a number.
Subtract the
original number.
Step7: Try at least 3 different starting numbers. You may use your calculator.
HW Complete the problems below and then do the rest on pages 139-141 in text.
(1-5) Evaluate the following expressions for x = -4 and y = 5
1) x2 – y2
2) y2 + 2y – 7
3) 2x2 + y2
4) 3x - 4y – 8
5) |x2 – 3y|
HW. Complete these problems from the book on this page.
1)
2)
6)