Transcript EXPRESSIONS What is an expression? - Algebra 1 -

– ALGEBRA I –
UNIT 1 – Section 1
Variables, Expressions, Simplifying, and Evaluating
Pretty darn
funny…
In this section, we will be
reviewing several concepts…
• variables
• expressions
• simplifying
• evaluating
• order of operations
VARIABLES
What is a variable?
A variable is a symbol (usually a letter) used to
represent a number that you do not know.
The most commonly used variables are…
It is usually a good
idea to pick a variable
that will remind you
what it stands for (i.e.
h = hours)
x y n
The VALUE OF A
VARIABLE is the number
that the variable stands for.
EXPRESSIONS
What is an expression?
“That’s da bomb…”
“Dude…that was phat.”
“Oh, snap!”
“I’m down with that…homey.”
No… Those are not the
expressions I’m talking about. By
the way, Mr. Dillon,you are not
that cool. Never…never…never
use the word “homey” again…
Do you mean
expressions
like…
EXPRESSIONS
What is an expression?
An expression is an algebraic statement that
contains some combination of variables,
numbers, and/or operations..
Examples of expressions are…
2x
4.5·h
6x + 7yx
A NUMERICAL EXPRESSION is an expression that
is made up of just a number.
The VALUE OF AN EXPRESSION is the answer
when numbers are put in for the variables.
POWERS
What is a power?
A power is an expression that indicates the
repeated multiplication of the same number (or
variable or expression).
An example of a power is…
The “big” number is
called the BASE.
This is the number
that is multiplied.
5
4
5
4
The “little” number is
called the EXPONENT.
This number tells you
how many times to
multiply the base.
= 4 4 4 4 4 = 1024
SIMPLIFYING
What does it mean to simplify?
Simplifying means writing an expression in an
equivalent form that has the fewest terms
possible. If the problem has all numbers, then
you simplify to get a single numerical answer.
In order to simplify an expression, you have to use…
ORDER OF OPERATIONS
SIMPLIFYING
The steps in order of operations are:
1) Parentheses (Grouping Symbols)
2) Exponents/Roots
3) Multiply/Divide (Left to Right)
4) Add/Subtract (Left to Right)
Here is an example…
SIMPLIFYING
54  3  3
Simplify the power.
2
Start with parentheses.
18  9
Then subtract.
18  3
9
2
Try These Problems…
Give these “simplify” problems a
try. You will use order of
operations to get your answer. Be
sure to show your work!
1) 5  9 2
**The answers can be found
at the end of the PowerPoint.
2
39  3  2 
2
2)
3  3
EVALUATING
What does it mean to evaluate?
Evaluating an expression means replacing the
variables with numbers and simplifying to get
the answer.
The first step in an “evaluate” problem is to
SUBSTITUTE a number in for each variable.
Then, you simplify by using…
ORDER OF OPERATIONS
Here is an example…
EVALUATING
2 x  y if x  2 and y  3
Substitute
2      22  3
Parentheses
7
Add
43
Try These Problems…
Gives these “evaluate” problems a
try. Substitute the numbers in for
the variables and simplify. Be sure
to show your work!
3) 4 x  y if x  1 and y  2
2

3y
4)
if y  4 and z  2
z
**The answers can be found at the end of the PowerPoint.
ALGEBRA
IS FUN
AND EASY!
**Answers: 1) 56
2) 3
3) 2
4) 72