Download Evaluating Expressions with One Variable

Algebra I –Wilsen
Unit 1: The Beginnings
Day Nine
Block 2
Evaluating Expressions with One Variable
An “expression” is a mathematical expression that includes variables but isn’t an
equation.
A “variable” is a letter or symbol that represents a number. Any of these can be
used as variables:
Ú
k p
m
f
a
b
x
y
z
These are all examples of algebraic expressions that use variables:
∆+ 2
3p
5x – 8
To evaluate an algebraic expression means to simplify it down to one value, or
number. But first, we need to know what number the variable represents.
Example 1
Evaluate the expression
if
a = –2
if
a =4
if
a =
3a
1
3
page 42
Example 2
Example 3
Evaluate
z–5
if
z=8
if
z = –2
if
z=0
Evaluate
3x + 1
if x = 3
if x = –3
if x =
Example 4
Evaluate
2
9
1+ 2m 2
if m = 1
if m = –1
if m = 3
page 43
Evaluate each expression for the value that has been given.
1)
5v – 2
if v= –3
2)
3n + 10
if n = 6
3)
3x + 10
if x = –3
4)
10 + 3a
if a = –4
5)
–5y – 4
if y = 2
6)
–5m – 4
if m = –3
7)
– 2(3c + 8)
if c = –4
page 44
8)
– 2(3c + 8)
if c = 2
9)
–2© – 4
if © = 4
10) –2© – 4
11)
x 1
+
5 2
if © = –5
if x = 5
(don’t forget you need a common denominator to
add fractions)
12)
x 1
+
5 2
if x = 10
page 45
13)
x 1
+
5 2
if x = 4
page 46