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!

Homework Help: Addition Of Exponents

  1. Feb 25, 2010 #1
    So I just got back from my math class, we were going over exponents. Right before we left he gave us a problem and we turned it in, I was just wondering if I got it right.

    (54-3y)3 * (5y-2)2

    I got:
    512-9y3 * 5y2-4


    I applied the powers to the parenthesis, then added the two exponents. The addition of the exponents is here:

    However when I just pop the original problem into wolfram alpha I get:

    So I guess I have two questions. First is my answer right? Second how did Wolfram come up with that answer?
  2. jcsd
  3. Feb 25, 2010 #2
    You are applying the exponentiation rules incorrectly in your first step - perhaps you want to review it. When you bring down the 3, you multiply it to the (4-3y) to get (12-9y) instead of taking powers. Do the same for the other term. Then you can reduce the exponents.

    See rules 3 here: http://mathworld.wolfram.com/ExponentLaws.html
  4. Feb 25, 2010 #3
    Thanks. Stupid mistake, always the stupid mistakes.
  5. Feb 25, 2010 #4
    That's fine - when you make mistakes you go back and look at the definitions, problems, and learn a lot that way. Cheers
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook