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OpenStudy (anonymous):
\[\sqrt[3]{n ^{2}-1}+4=3?\]
OpenStudy (anonymous):
\[\sqrt[3]{n^2 -1+4}=3\]
OpenStudy (anonymous):
yes.
OpenStudy (anonymous):
cool. Cube both sides first.
OpenStudy (anonymous):
Wait. Which equation? Yours or mine?
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OpenStudy (anonymous):
they're the same.
OpenStudy (anonymous):
could give me a visual of cubing both sides.
OpenStudy (anonymous):
Mine has the +4 on the outside of the root. Yours has it on the inside. Which one is it?
OpenStudy (anonymous):
If it's on the outside, then you'll subtract 4 first.
If it's on the inside, then you'll cube both sides first.
OpenStudy (anonymous):
yours
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OpenStudy (anonymous):
Okay. So subtract 4 first and you'll get...\[\sqrt[3]{n ^{2}-1}=-1\]
OpenStudy (anonymous):
Then cube both sides and you'll get...\[n ^{2}-1=-1\]
OpenStudy (anonymous):
okay.
OpenStudy (anonymous):
Next, add 1 to both sides and you'll get...\[n ^{2}=0\]
OpenStudy (anonymous):
Therefore, n = 0.
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OpenStudy (anonymous):
Which if you plug it into the original equation, it works. You can take the cube root of negative numbers, but you can't take the square root. As a matter of fact:
You can take the ODD-number root of any negative number.
But you CANNOT take the EVEN-number root of any negative number.
Just a rule to keep in mind.
Take care.