Results are out! Find what you Get quick advice or join the chat
Hey! Sign in to get help with your study questionsNew here? Join for free to post

Write y as a function of x

Announcements Posted on
Will you get the grades you need for uni? Get prepared today and de-stress, sign up to email alerts for course places! 02-06-2015
Waiting on IB results? Our IB results hub explains everything you need to know 01-06-2015
  1. Offline

    Given the equation: 2x - 3y = 6

    Write y as a function of x.

    I know this is straightforward, and I have the line-by-line answer, but I can't understand how you get from:

    (2x - 3y = 6)
    - 3y = - 2x + 6 (So here you have shifted the 2x over as you want ultimately just y on the left)
    y = 2x/3 - 2 (Where's the -3? Why is there a fraction on the right? What's happened to the +6?)

  2. Offline

    You divided both sides by -3.

    \frac{-3y}{-3} = y

    \frac{-2x}{-3} = \frac{2x}{3}

    \frac{6}{-3} = -\frac{6}{3} = -2.
  3. Offline

    Oh so you do it to the +6 AND the -2x. Got ya!
  4. Offline

    How would I then find the "intercept" and the "root"?
  5. Offline

    The root is basically the value of x for which y = 0. So set y to and solve for x.

    The y-intercept is the value of y for which x = 0. So set x to 0 and solve for y.
  6. Offline

    (Original post by tymbnuip)
    Oh so you do it to the +6 AND the -2x. Got ya!
    Yes you're "doing it" to the sides of the equation rather than the actual terms (at least that's one way of looking at it).

    If you didn't, your equation would not hold. There's only a limited number of valid operations you can do to an equation (an equation states that something on the left side is equal to something on the right side) like add/subtract a number to each side or multiply the left expression and the right expression by the same factor (in your case that factor is -3)
  7. Offline

    The root (x -intercept) is when y = 0

    2x/3 - 2 = 0

    2x - 6 = 0 {multiply both sides by 3}
    So how does the /3 disappear by multiplying by 3? Wouldn't it turn into 9?
  8. Offline

    (Original post by tymbnuip)
    So how does the /3 disappear by multiplying by 3? Wouldn't it turn into 9?
    \frac{2x}{3} - 2 = 0

    \frac{2x}{3} . \frac{3}{1} - 2 . \frac{3}{1} = 0 . \frac{3}{1}

    2x - 6 = 0

    When multiplying two fractions, multiply the top by the top and the bottom by the bottom

    2x times 3 = 6x

    3 times 1 = 3

    6x/3 = 2x

    Get it?
  9. Offline

    What does the =0.3/1 mean?
  10. Offline

    Urgh sorry

    it means 0 times \frac{3}{1}
  11. Offline

    Heh okay. So I guess now I have 2x - 6 = 0 I want to get rid of the 6?


Submit reply


Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: August 4, 2008
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

New on TSR

Improving your uni offer

Why now is the time to think about Adjustment

Study resources

Think you'll be in clearing or adjustment?

Hear direct from unis that want to talk to you

Get email alerts for university course places that match your subjects and grades. Just let us know what you're studying.

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.