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: Rearrange the formula

  1. Mar 2, 2010 #1
    I need to rearrange this formula to make e the subject. Have I done it correctly?

    10b + 5be - 3e + 7c
    10b + 5be - 3e = 7c
    5be - 3e = 7c - 10b
    e(5b - 3) = 7c - 10b

    e = 7c - 10b / 5b - 3
     
  2. jcsd
  3. Mar 2, 2010 #2

    Mark44

    Staff: Mentor

    You're not starting with an equation! Without the first line below being an equation, you can't solve for anything.
    Assuming that this is your starting equation -- 10b + 5be - 3e = 7c -- your work following it is fine, EXCEPT that you need to use parentheses. You should write e this way:
    e = (7c - 10b) / (5b - 3)
     
  4. Mar 2, 2010 #3
    Thanks a lot Mark
     
  5. Mar 3, 2010 #4
    Well if we assume that the first line is an equation (set equal to zero): 10b + 5be - 3e + 7c=0, then the second line changes:

    10b + 5be - 3e = -7c, and that would change the rest of the steps which follow...
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook