Brain Workout

See if you can figure these out :)

brain_problem1.png

brain_problem2.png

brain_problem3.png

post a comment8 Comments

  1. 1May 29th, 2006Jeff Wheeler says

    In the first one, I don’t think you can go from a^2 - b^2 to (a+b)(a-b).

    On the second one, I don’t think you can go from (Pi+3)(Pi-3) to Pi^2-9.

    On the third one, I don’t know enough about imaginary numbers to figure it out. They’re probably doing something with squaring i that doesn’t work, or something.

    Anyways, all of these are most likely wrong. It’s summer. :)

  2. 2May 29th, 2006Oliver Zheng says

    Hehe. The steps you said for the first two work. That formula works for everything all the time. ;)

  3. 3May 29th, 2006Jeff Wheeler says

    Well… obviously not.

  4. 4May 31st, 2006Tejesh Mehta says

    1. line: (a+b)(a-b) = b(a-b)..a-b is zero
    the line is not determined by what zero is multiplied by.
    it doesnt not matter what else is on the line bc both
    sides are multiplied by zero.
    2. When you have two unknown is a single equation.
    there are an infinite set of solutions. So u can get
    one of the variables…to basically equal anything
    Unless there are mathmatical restrictions based
    on the given equation(in this case..there aren’t).
    3. When you take a squareroot of anything it results in
    a plus or minus (+/-) number. Ex: sqrt(9)= (+/-)3.
    So if that was done correctly the final answer would
    be (+/-)1=(+/1)1. The mistake was assuming the
    positive answer to both the square roots.

    im a nerd :-\
    tj

  5. 5May 31st, 2006Oliver Zheng says

    You are absolutely correct! I couldn’t figure out the last one for the longest time.

  6. 6June 1st, 2006Anurag Bhandari says

    Hey! These are really nice and deceivingly astonishing problems. How did you arrive at these conclusions or from where did you get these ideas. Really great!!

  7. 7June 2nd, 2006Aarohi Johal says

    I didn’t read the other comments.

    Well… since a=b… and you’re also cancelling out a-b with a-b… and division with 0 is impossible. :/

  8. 8June 3rd, 2006Oliver Zheng says

    I got these from EEtimes, a computer-related magazine. I guess I should be giving credit, but they didn’t write it either.

    Aarohi, you got the first one right!

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