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Evaluate powers with negative integer bases

A power with a negative integer base represents repeated multiplication of that base; its value is positive when the exponent is even and negative when the exponent is odd, with exponent zero yielding 1. The distinction between (a)n(-a)^n and an-a^n is essential because parentheses determine whether the negative sign is part of the base; this scope excludes negative or noninteger exponents.

Detailed Explanation: Evaluate powers with negative integer bases

A power with a negative integer base means repeated multiplication of the negative number. The parentheses show that the negative sign is part of the base.

For example, evaluate

(2)5(-2)^5
  1. The base is 2-2, and the exponent is 55. So multiply 2-2 five times:

(2)5=(2)(2)(2)(2)(2)(-2)^5=(-2)(-2)(-2)(-2)(-2)
  1. Pair the factors:

(2)(2)=4(-2)(-2)=4

There are five negative factors, so one negative factor is left over. Therefore, the product is negative.

  1. Multiply the absolute values:

25=322^5=32

Thus,

(2)5=32(-2)^5=-32

An even exponent gives a positive answer because the negative factors pair up. An odd exponent gives a negative answer. Also, any nonzero number raised to the zero power equals 11:

(2)0=1(-2)^0=1

Be careful with parentheses:

(2)4=16(-2)^4=16

because the base is 2-2, but

24=16-2^4=-16

because the exponent applies only to 22, and the negative sign remains outside the power.

Learn by doing: Evaluate powers with negative integer bases

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Exponents - Negative Base


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