Pre Algebra (Period 2 & 4)

Simplifying Variable Expressions 2-3

Review of Algebraic terminology:

In the expression, 3y + 5

3 is the coefficient (number attached to variable - remember, "co" means to go along with)

y is the variable

5 is the constant (number not attached to variable)

terms are separated by ADDITION ONLY!



COMBINING LIKE TERMS:

1. Same variable (or no variable)

2. Same power
You can combine by addition or subtraction LIKE TERMS.

You cannot combine UNLIKE TERMS.


EX:
3a + 4a = 7a
 BUT

3a + 4b = 3a + 4b

3a + 4a² = 3a + 4a²


YOU SHOULD ALWAYS COMBINE LIKE TERMS BEFORE YOU EVALUATE!

IT'S MUCH SIMPLER!

-25a + 5a - (-10a) when a = -14

First combine like terms: -10a

Then plug in for a = -14:
-10(-14) = 140

VARIABLES AND EQUATIONS: Section 2-4

Is a given number a solution to an equation?

Substitute and evaluate to see.

Use the set signs { } and a ? over the equal sign as we did in class

9k = 10 - k for k = 1


9(1) = 10 - (1)

9 = 9 checks



Numeric Equations are either True or False

Equations with variables are OPEN (don't know if they are True or False)