Cumulative Practice
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- 12
We want to find the value of the given expression.
- 5+( - 7)
We can recall that adding a number is the same as subtracting its opposite.
Next we can draw an arrow 7 units to the left to represent adding - 7.
The resulting position, after moving to the left on the number line, is the sum. - 5+( -7)= - 12
These properties tell us the legal
moves we can make when adding or multiplying numbers.
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But why aren't there properties for subtraction or division? |
Some mathematicians refuse to acknowledge that subtraction and division are even operations! Subtraction is the same thing as adding a negative and division is the same thing as multiplying by a fraction. a-b=a+(- b) and a/b=a* 1/b Therefore, we can use the Properties of Real Numbers for subtraction and division, but we need to change our way of thinking.