Pre Algebra (Periods 2 & 4)

Our Class Blog
Welcome to our class blog... where you can earn extra credit by adding your own relevant comments about our class notes for the day.. or where you can find answers from others in your class. Check here often, especially if you have been absent. You might just find out the math strategy that works for you!!

Email me if you are interested in adding notes and/or comments to this blog-- for extra credit!!

Expressions 1-1
Expression are NOT equations. An Expression does NOT have an equal sign (=).
Words you need to know:
Addition: sum, increased by, more than
Subtraction: difference, less THAN, subtracted from
Be careful with this one... "3 less than a number n" is n-3. It isn't in the order that you read. Think about "3 less than 10" What would you write ? 10-3...

Multiplication: product, times
Division: quotient or Per... When we say " miles per hour" it is really the MILES DIVIDED by the HOURS!!


The Order Of Operations 1-2

O³ = Order Of Operations

It’s Aunt Sally’s Rule—
Please Excuse My Dear Aunt Sally

Please ( ) parentheses

Excuse E² exponents

My Dear (or even Dear My) × ÷ or ÷ ×

Aunt Sally (Sally Aunt) + - or - +

also called ... PEMDAS

The most common mistake of O³

Student forget that when you see multiplication and division—you do whichever comes first in order!!

So if you see division then multiplication, you do division first then multiplication
When you see addition and subtraction, you do whichever comes first in order!
So if you see subtraction then addition, do the subtraction first!

When you see more than one set of parentheses, do the innermost ones first, then work outwards.
They're called nested parentheses because a bird builds his nest from the inside out.


Evaluating Expressions 1-3

First substitute in for the variable..
Follow AUNT SALLY's RULE or PEMDAS

4y - 15 where y = 9
4(9) - 15
36 - 15
21

3ab + c/2 where a = 2 b = 5 and c = 10
3(2)(5) + 10/2
30 + 5
35

Be careful when substituting in negatives...