I explain briefly what the commutative and associative properties of addition & multiplication mean.
Then we check if subtraction & division also have those properties -- turns out they don't. It's easy to prove that by using specific numbers and checking that the expressions given in the properties are not equal. For example, since 10 - 5 is not equal to 5 - 10, subtraction is not commutative.
After that, I go through examples where we check if two given expressions are equal for all values of the variable, using our knowledge of the properties of the operations. For example, is a + 5 equal to 5 + a?
Lastly, I simplify various expressions using the commutative and associative properties of addition and multiplication - and also the definition of multiplication.
Learn more pre-algebra with Math Mammoth Grade 7 Curriculum at http://www.mathmammoth.com/complete/grade_7.php - available as an instant download and as printed copies. Check out the free samples also!
Tagged under: Commutative Property,Associative Property,Algebra (Field Of Study),Subtraction,Multiplication,Division,Addition,Math,Expression
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