Question

How do I evaluate: (-1000)1/3

Answer 1

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Answer:

  -10

Step-by-step explanation:

The first step is to write what you mean. We think you mean (-1000)^(1/3).

If you've been paying attention to place-value, and/or cubes of small integers, you already know that 10^3 = 1000. Since we're concerned with an odd power, we also know ...

  -1000 = (-10)^3

Then your expression is ...

  (-1000)^(1/3) = ((-10)^3)^(1/3) = (-10)^(3/3) = (-10)^1 = -10

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Some calculators can evaluate this for you (see attached).

Some calculators and spreadsheets use logarithms to compute roots or fractional powers, so will give you an error when you try to compute this. You should know that an odd-index root of a negative number (here, 3rd root of -1000) has the same sign as the number: negative. Then you can use your calculator to compute the positive root and add the sign yourself:

  (-1000)^(1/3) = -(1000^(1/3)) = -(10) = -10

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Of course, a 1/3 power is the same as a cube root. Your calculator may have a cube root button that works just fine with negative numbers.