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9/28 Exponential Expressions

We must evaluate exponential expressions of the form an When the base a is negative, we use the following rule:

If the exponent n is even, then an is positive. If the exponent n is odd, then an is negative.Why?

• =−52=×−5−525

The exponent 2

is even, so the answer is positive.• =−33=×−3×−3−3−27

The exponent 3

is odd, so the answer is negative.