Transcript Objective - To recognize and evaluate variable expressions

Objective - To recognize and evaluate
variable expressions and basic formulas.
What is a variable?
A variable represents an unknown value.
1) 3 + ___ = 10
2) 6 +
= 9
3) 8 + x = 12
4) 5 +
= 8
These are all
variables
Variable Expressions
Variable expressions consist of constants,
variables, and operations.
Example
Meaning
Operation
7x
w
10
7 times x
multiplication
w divided by 10
division
8 p
8 plus p
addition
k5
k minus 5
subtraction
Evaluate the expression if a = 3, b = 4,
and c = 5
1) ab - c
(3)(4) - 5
12 - 5
7
2) 2a(b - c)
2(3)(4 - 5)
2(3)(-1)
-6
3) 2a  b  2
2(3) + 4 2
6+4 2
6+2 = 8
2( b  c)
4)
a
2(4 + 5)
3
18
2(9)
=
= 6
3
3
Formulas
Formula - an equation which defines the relationship of one variable to other variables or numbers.
Travelling to Las Vegas at an average speed of
60 miles/hour takes 5 hours. How far is Las Vegas?
rt  d
( 60)(5)  d
300  d
d = 300 miles
Perimeter
Perimeter - Distance around a geometric figure.
Find the perimeter of the triangle below.
b  5 cm
a  3 cm
c  7 cm
P abc
P  35 7
P  15 cm
Area Formulas
Rectangle
w
l
Parallelogram
w
l
A  l w
Find the area
A  l w
4
5
A  l w
A  5 4
2
A  20 un
Area Formulas
Rectangle
w
l
Parallelogram
A  l w
Find the area
A  l w
4
5
A  l w
A  5 4
2
A  20 un
Area Formulas
Rectangle
w
l
Parallelogram
h
b
A  l w
Find the area
A  l w
4
5
A  l w
A  5 4
2
A  20 un
Area Formulas
Rectangle
w
l
Parallelogram
h
b
A  l w
Find the area
A  l w
4
5
A  b h
A  5 4
2
A  20 un
Area Formulas
Rectangle
w
l
Parallelogram
h
b
Triangle
A  l w
Find the area
A  l w
4
5
A  b h
A  5 4
2
A  20 un
A  b h
8
7
10
A  10  7
A  70 un2
Area Formulas
Rectangle
w
l
Parallelogram
h
A  l w
b
A  l w
4
5
A  b h
b
Triangle
h
Find the area
A  b h
8
7
10
A  b h
A  5 4
2
A  20 un
A  10  7
A  70 un2
Area Formulas
Rectangle
w
l
Parallelogram
h
A  l w
b
A  l w
4
5
A  b h
b
Triangle
h
Find the area
A  b h
8
7
10
A  b h
A  5 4
2
A  20 un
A  10  7
A  70 un2
Area Formulas
Rectangle
w
l
Parallelogram
h
A  l w
b
A  l w
4
5
A  b h
b
Triangle
h
Find the area
A  b h
8
7
10
A  b h
A  5 4
2
A  20 un
A  10  7
A  70 un2
Area Formulas
Rectangle
w
l
Parallelogram
h
A  l w
b
A  l w
4
5
A  b h
b
Triangle
h
Find the area
A  b h
8
7
10
A  b h
A  5 4
2
A  20 un
A  10  7
A  70 un2
Area Formulas
Rectangle
A  l w
w
l
Parallelogram
h
b
A  l w
4
5
A  b h
b
Triangle
h
Find the area
A  b h
8
7
10
1
A  b h
2
A  5 4
2
A  20 un
5 7
8
A  10  7
A  70 un2
1
A  85
2
A  20 un2
b g