SOLUTION: How do I simplify 3√(-1/125)?

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Question 352886: How do I simplify 3√(-1/125)?
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
3sqrt%28-1%2F125%29
With a negative radicand (expression with a radical), this expression is going to be an imaginary number. And with imaginary numbers we use i to factor out the factor of -1:
3sqrt%28-1%2A%281%2F125%29%29
3sqrt%28-1%29sqrt%281%2F125%29
3i%2Asqrt%281%2F125%29
Next, a simplified radical expression has ...
- No radicals in a denominator
- No fractions in a radicand
We have a fraction in the radicand so we have more work to do. Although there are other ways to simplify radicands with fractions, I like to start by making the denominator a perfect square. So we'll start by figuring out what we can multiply 125 by to turn it into a perfect square. Surely multiplying by 125 will work. But there is a smaller number that will work. And since smaller numbers are easier to work with, I prefer to go that way. Since 125+=+5%2A5%5E2 I can see that just another factor of 5 will make 125 a perfect square, It will be the perfect square of 5*5 or 25:
3i%2Asqrt%28%281%2F125%29%285%2F5%29%29
3i%2Asqrt%285%2F625%29
Now we'll split the fraction into spearate square roots:
3i%2Asqrt%285%29%2Fsqrt%28625%29
and replace sqrt%28625%29 with 25:
3i%2Asqrt%285%29%2F25
This is our simplified expression. An alternate form, which may be preferred by your teacher, would be:
%283sqrt%285%29%2F25%29i