Download A collection of numbers, operation signs, and grouping symbols is

A collection of numbers,
operation signs, and grouping
symbols is called an expression.
A collection of numbers,
operation signs, and grouping
symbols is called an expression.
When variables are part of an
expression, it is called a
variable expression.
Here is a variable expression.
a+b–8
Evaluate the expression for
a = 9 and b = 12
a+b–8
Substitution property
or
Substitution principle
or just
Substitution
Substitution property
or
Substitution principle
or just
Substitution
An expression may be replaced
by another expression that has
the same value.
3+2=5
1
4
+
1
2
1
4
1
4
+
1
2
+
2
4
1
4
1
4
+
1
2
+
2
4
3
4
9
12
9
12
3
4
25
25
2•2•2•2•2
25
2•2•2•2•2
32
Evaluate the expression for
a = 9 and b = 12
a+b–8
Evaluate the expression for
a = 9 and b = 12
a+b–8
9 + 12 – 8
Evaluate the expression for
a = 9 and b = 12
a+b–8
9 + 12 – 8
21 – 8
Evaluate the expression for
a = 9 and b = 12
a+b–8
9 + 12 – 8
21 – 8
13
If two variables are written
together, they are to be
multiplied,
ab = a • b
If a number and a variable are
written together, they are to be
multiplied,
3b = 3 • b
If a number and a variable are
written together, they are to be
multiplied,
3b = 3 • b
The number is called the
coefficient of the variable.
Since multiplication is
commutative, it is true that
3 • b = b • 3,
but it is not customary to write,
b3.
Always write the coefficient
first.
Evaluate the expression for
a = 9 and b = 12
3a – 4 + 5b
Evaluate the expression for
a = 9 and b = 12
3a – 4 + 5b
3 • 9 – 4 + 5 • 12
Evaluate the expression for
a = 9 and b = 12
3a – 4 + 5b
3 • 9 – 4 + 5 • 12
27 – 4 + 60
Evaluate the expression for
a = 9 and b = 12
3a – 4 + 5b
3 • 9 – 4 + 5 • 12
27 – 4 + 60
23 + 60
Evaluate the expression for
a = 9 and b = 12
3a – 4 + 5b
3 • 9 – 4 + 5 • 12
27 – 4 + 60
23 + 60
83
Evaluate variable expressions by
substituting given values for the
variables.