Transcript 1-1 Variables

1-1 Variables
That stuff that varies…
How much can I make at $6.00 an hour?
Hours Worked
Total Pay Earned
1
2
3
4
What is the relationship between hours worked and
total pay earned?
Variable Vocab:
• Variable – letter used to represent one or
more numbers
• Values of the variable – numbers that
can replace the variable
• Variable expression – expression that
contains a variable
• Numerical expression (or numeral) – an
expression that names a specific number
Multiplication Confusion???
X vs. * vs. nothing
Equal symbol
• Two different EXPRESSIONS can say the same
thing:
25 + 50
But,
25 + 50


75
2550
Substitution Principle- an expression can be replaced
by another expression of the same value.
• 12 + (4  2)
• 12  (4 + 2)
• (3 + 2)  (6 – 1)
Evaluate each expression when m = 1 and n = 2.
• 3(n + 4)
• (mn) + 4
1-2 Grouping Symbols
• Grouping Symbol - device used to enclose an
expression that should be simplified first.
• Parentheses
6(5 – 2)
• Bracket 3[9 + 2]
• Fraction Bar
12  3
45
Order of Operations
•
•
•
•
•
•
P
E
M
D
A
S
Please
Excuse
My
Dear
Aunt
Sally
Parentheses
Exponents
Multiplication
Division
Addition
Subtraction
1. Start with innermost grouping symbol and work your way out.
2. Do all multiplication and division from left to right.
3. Do all addition and subtraction from left to right.
Board Examples: Find the value of
each expression.
a. 5(8 + 3)
b. 5(8) + 3
c.
10  6
10  2
d. 10 – [10  (8 – 3)]
e. 3 + 8  2 4
f. Find the value of the expression when a = 4, b = 7,
and c = 10 4a  2b
ca
Assignment:
• 2 Dittos