- #1
chingel
- 307
- 23
Homework Statement
Solve the equation:
[itex]\sqrt[3]{x+1}+\sqrt[3]{x+2}+\sqrt[3]{x+3}=0[/itex]
The Attempt at a Solution
What I did was move (x+3)^(1/3) to the other side, cube both sides and when I put them equal to 0 again, I managed to factor (x+2)^(1/3) out of it giving one solution x=-2.
However if I looked up the proposed solution after cubing and a little gathering and grouping it arrived at this:
[itex]3x+6=-3\sqrt[3]{x+1}*\sqrt[3]{x+2}*(\sqrt[3]{x+1}+\sqrt[3]{x+2})[/itex]
Which is clear, but then in the next step it is converted to this without explanation:
[itex]x+2=\sqrt[3]{(x+1)(x+2)(x+3)}[/itex]
From there on the solution is just putting it equal to 0 and factorizing, but how did it get to this from the previous? It would imply [itex]-(\sqrt[3]{x+1}+\sqrt[3]{x+2})[/itex] is equal to [itex]\sqrt[3]{(x+3)}[/itex], which I don't think it is. Is it wrong or what is up with that?