Åk 6–9
 
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5.1 Power with Negative Bases
Powers are covered in the section about natural numbers and you learn there that powers are repeated multiplication. Here is an example:

23 = 2 · 2 · 2 = 8


Calculating powers with a negative base isn’t difficult and an example could looke like this:

(-2)3 = (-2) · (-2) · (-2) = -8

A good method to show powers with negative numbers is to multiply two factors at a time:

(-2) · (-2) = 4

4 · (-2) = -8


Something very important to be aware of is when you are calculating with parenthesis.  Look at this example:

(-3)2 = (-3) · (-3) = 9

-32 = -(32) = -(3 · 3) = -(9) = -9

The conclusion is that you get different answers depending if the base is in parenthesis or not.