AoPS Ch 1 Properties of Arithmetic Flashcards
Addition is commutative. What does this mean?
a + b = b + a
Order of operations: In what order do you perform the operations in an expression?
- Evaluate expressions inside parentheses first.
- Compute powers.
- Multiply and divide from left to right.
- Add and subtract from left to right.
What is another way to write 3 + 7 using the commutative property of addition?
7 + 3
Addition is associative. What does this mean?
(a + b) + c = a + (b + c)
What is another way to write (2 + 5) + 3 using the associative property of addition?
2 + (5 + 3)
In other words, you can add 5+3 first to get 8 and then add 2 to get 10, instead of 2+5 to get 7 and then 7+3 to get 10.
Compute (35 + 13) + 27
Using the associative property:
35 + (13 + 27) = 35 + 40 = 75
Multiplication is commutative: What does this mean?
ab = ba
Multiplication is associative. What does this mean?
(ab)c = a(bc)
According to the commutative property, what does 7x35 equal?
7 x 35 = 35 x 7
Using the associative property, compute 25 x (12 x 8) in your head.
25 x (12 x 8) = (25 x 12) x 8 = 300 x 8 = 2400
Distributive Property: Multiplication distributes over addition. What does this mean?
a(b + c) = ab + ac
and
(b + c)a = ba + ca
Using the distributive property, what is 5 x 17?
5 x 17 = 5 x (10 + 7) = 5 x 10 + 5 x 7 = 50 + 35 = 85
Using the distributive property, compute (7 + 9) x 13.
(7 + 9) x 13 = (7 x 13) + (9 x 13) = 91 + 117 = 208
or
(7+9) x 13 = 16x13 = 16 x (10+3) = 16x10 + 16x3 = 160+48 = 208
What is the Negation Property?
-a + a = 0
What is the Reciprocal Property?
(1/a) x a = 1
What is the definition of SUBTRACTION?
a - b = a + (-b)
Subtraction is addition of the negation.
What is DIVISION?
(a/b) = a x (1/b)
Division is the same as multiplication by the reciprocal.
Negation of a negation says the -(-a) = ?
-(-a) = a
Negation of a sum says that -(a + b) = ?
-(a + b) = (-a) + (-b)
Multiplying by -1 means that (-1)a = ?
(-1)a = -a
Multiplying by a Negation means that (-a)b = ?
(-a)b = -(ab)
and
a(-b) = -(ab)