Solve Equations and Justify Each Step in the Solution
In this activity, you will work on algebraic proofs.
Proving things are true is a very important skill to have as a mathematician!
Be thinking about the "steps" in a proof. Also be thinking about how to justify each step.
What property of numbers, or equality can be applied as reasons in your proof?
1.  Which property is used to justify the following statement?
           Let a = 5 and b = 16.             2ab = 2(5)(16) = 160.    
Symmetric Property of Equality
Reflexive Property of Equality
Transitive Property of Equality
Substitution Property of Equality
2.  Which property justifies the work from Step 1 to Step 2 below?
Step 1:  5x + 9 = 16
Step 2:  5x = 7
Subtraction Property of Equality
Multiplication Property of Equality
Division Property of Equality
3.  Which property justifies the work from Step 1 to Step 2 below?
Step 1:  7m = 63Step 2:  m = 9
Addition Property of Equality
Subtraction Property of Equality
Division Property of Equality
4.  Which property justifies the work from Step 1 to Step 2 below?
Step 1:  -8 + 6n = 4Step 2:  6n = 12
Multiplication Property of Equality
Addition Property of Equality
Division Property of Equality
5.  Which property justifies the work from Step 1 to Step 2 below?
Step 1:  -x = 15Step 2:  x = -15
Addition Property of Equality
Subtraction Property of Equality
Division Property of Equality
6.  Fill in the missing parts of the proof by dragging     the justifications to the correct step of the proof.
1.  4(x - 3) = 36
2.   4x - 12 = 36
3.   4x = 48
4.   x = 12
STEPS
Addition Property of Equality
?
Division Property of Equality
?
Distributive Property
?
REASONS
Given
Reflexive Property of =
?
not used: 
7.  Fill in the missing parts of the proof by dragging      the justifications to the correct step of the proof.
2.   -6x + 12 = 24
3.   -6x = 12
1.  -6( x - 2 ) = 24
4.   x = -2
STEPS
Subtraction Property of =
?
Distributive Property
?
Division Property of =
?
REASONS
Associative Property of =
?
Given
?
not used: 
8.  Fill in the missing parts of the proof by dragging      the justifications to the correct step of the proof.
2.   6x – 3 = -21
3.   6x = -18
1.   8x - 3 = -21 + 2x
4.   x = -3
STEPS
Subtraction Property of =
?
Division Property of =
?
Addition Property of =
?
REASONS
Associative Property of =
?
Given
?
not used: 
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