- #1

Mentallic

Homework Helper

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Simplified, a section of the problem was as so:

[tex](\sqrt{-a})^3[/tex]

Now, I would go about trying to cube the inside of the root, and cubing a negative gives a negative so I end with:

[tex]\sqrt{-a^3}[/tex]

but after vigorous searching for algebraic errors and finding none, I took another look at this part of the question and (not trusting negatives in roots) went about it like this:

[tex](\sqrt{-a})^3=(i\sqrt{a})^3=i^3\sqrt{a^3}=-i\sqrt{a^3}=-\sqrt{-a^3}[/tex]

which gave me the correct answer. But I'm stumped as to why the first method didn't work