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Help with a Proof

  • Thread starter Airaya
  • Start date
  • #1
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Homework Statement




Prove for all xεR [(-x)3 = -(x3)]
(Hint you may use the fact that -x = (-1)*x, but other wise stick to axioms)
I wrote something along the lines of .
(-x)3 can be written as (-1)(x)(x)(x) and -(x)3 can be written as (-1)((x)(x)(x))
and these are both equivalent
But it doesn't feel like I'm proving anything.
Not sure how to really write this out so there is enough "proof"
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
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I think the point you are missing is that (-x)3 "can be written as" (-x)(-x)(-x) and then you can show that is equal to -(x)(x)(x).
 

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