Cumulative Practice
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Subtracting can be thought of as going left on the number line.
25
We want to determine the value of the given expression.
17-( - 8)
We can recall that subtracting a positive number is the same as adding its opposite.
17-( - 8) ⇔ 17+8
Finally, we can perform the addition.
17+8= 25
We can see that adding a negative number is the same as subtracting its positive counterpart. Below we can demonstrate this by finding the difference between 17 and - 8 on the number line. Let's draw an arrow from 0 to 17 on the the number line!
Next we can draw an arrow 8 units to the left to represent subtracting - 8.
The expression has the value of 25.
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.