1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is -i = 1/i ?

  1. Jun 17, 2010 #1
    Maybe this is something that's well known but I'd never heard of before, or maybe it's simply incorrect, but is negative i equal to the reciprocal of i?

    -i = 1/i

    My reasoning being that multiplying both sides of the equation gives 1.

    LHS: -i * i = -(-1) = 1
    RHS: i/i = 1

    Please help, it's been bugging me and google didn't give any answers
  2. jcsd
  3. Jun 17, 2010 #2
    No, it equals 5...

    J/k, yes -i = 1/i:smile:
  4. Jun 17, 2010 #3
    Phew, thank you!

    I thought for a second I'd broken maths...
  5. Jun 17, 2010 #4


    User Avatar
    Homework Helper

    I also thought you... broke him
  6. Jun 17, 2010 #5
    Another approach is to express 1/i as i^3/i^4.
    This simplifies to -i/1
  7. Jun 17, 2010 #6
    Ha, have you tried googling "1/i" ? :D
  8. Jun 17, 2010 #7


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You had to google 'Reciprocal of the imaginary unit'

    I can't believe that's not the first thing you tried!

    EDIT: Actually googling 1/i gives a result in google calculator....
  9. Jun 17, 2010 #8
    I wonder what the B(1/i)ng search engine would give...
  10. Jun 17, 2010 #9


    User Avatar
    Science Advisor

    Bing interpreted "1/i" as "1 i" and gave a lot of non-math websites- stick to google!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook