Ms. Drake 7th grade Math
Number TheoryLesson 15
Variables and Algebraic Expressions
Week by Week Essentials Week 4
Number TheoryAddition Property of EqualityAlgebraic ExpressionBaseCoefficientComposite Number ConstantDivision Property of EqualityEquation
EvaluateExponentGreatest Common Factor (GFC)Inverse OperationsIsolate the VariableLeast Common Multiple (LCM)Like Terms
Number Theory
Number TheoryMultipleMultiplication Property of EqualityNumerical ExpressionOrder of OperationsPowerPrime FactorizationPrime NumberScientific NotationSolution
Number Theory
SolveStandard FormSubtraction Property Of EqualityTermVariableVerbal Expression
Algebraic Expression: an expression that contains
at least one variable.Example:
3 + x5(b-2)
Variables and Algebraic Expressions
Evaluate: to find the value of a numerical or algebraic
expression.
Variables and Algebraic Expressions
Constant: stays the sameA value that does not change.
2 always represents the value 2
5 always represents the value 5
Variables and Algebraic Expressions
What are examples of quantities that are
constant?
The year you were born…
The number of hours in a day…
Variables and Algebraic Expressions
Variable: varies- is not the same
A letter that takes the place of an unknown number or
numbers.
A symbol used to represent a quantity that can change.
What are some examples of quantities that vary?
The price of gasoline…
Temperatures….
Abdul entered a walk-a-thon for a local charity. His
sponsor provided the $20 entry fee and will provide $4
for each mile he walks.
How can we find out how much money Abdul could help
raise
Make a table to display the information
How would we write the expression if the number of miles walked is replaced by
the variable m?
Miles Walked Expression Amount 1 20 + 4(1) 24 5 20 + 4(5) 40
If Abdul walked 13 miles, how much would he earn for
charity?
What if Abdul wanted to earn $100 for charity? How many miles must he walk?
Evaluate each expressions for the given value of the
variable.
3x – 2 for x = 5
… for x = 7
28
Evaluate an algebraic expression with two
variables.
…Until next time solve this magic square with a partner.In a magic square each row,
column and diagonal will have the same sum.
Evaluate for x = 4 x = 6 and x = 0.
Which solutions are true?
This is a magic square only if after you solve each
expression, the sums of the solutions in each row, column and diagonal are the same.
7+4 11
4 4
2(4)+1 9
4+2 6
0.5(4)+6 8
4+6 10
3(4)-5 7
3(4) 12
4+1 5
24 24
24
24
24
24
24
24
6+6 12
6 6
2(6)+1 13
6+2 8
0.5(6)+6 9
6+6 12
3(6)-5 13
3(6) 18
6+1 7
33 32
38
33
29
31
35
28
Six is not a solution.
7+0 7
0 0
2(0)+1 1
0+2 6
0.5(0)+6 6
0+6 6
3(0)-5 -5
3(0) 0
0+1 1
8 8
-4
6
24
8
2
14
Zero is not a solution