Hey! Sign in to get help with your study questionsNew here? Join for free to post

Find equation of this function (my answer is different from the books answer)

Announcements Posted on
Why bother with a post grad? Are they even worth it? Have your say! 26-10-2016
    • Thread Starter

    The graph of a parabola has a turning point at (-2, 4), write the equation of this function if it passes through point (2,8). The original equation is y = (x+2)^2 + 4

    I got: y = 0.25(x+2)^2+4
    The answer in my book is y=1/2(x+2)^2 +4

    PS: u gotta go use like: y = k(x+2)^2 + 4 to find the equation im guessing.

    Your function passes through the correct point, but the book's does not. However, it is unclear to me what your question even means. There are infinitely many parabolas with the features you have described, and you have not specified what relationship the 'original equation' has to any solution or why it has this relationship. The closest you have come is saying that you are guessing at some transformation, but you have not made it clear why you are guessing this.

    All things considered, it might be easier to answer if you post the wording of the original question.
    • Thread Starter

    Ah dont worry must be correct ;p thanks, because my book does have some mistakes and even my teacher said so that we should be careful as our workings will be correct however this book will show otherwise....


    It is correct ... there was a post before saying you were right so I did not post

    Your method is also correct ... use completing the square from the turning point ... multiplying the bracket by a constant since constant x 0 = 0 ... then putting in the second value

    I am not sure why Bobifier thinks there are infinite examples
Write a reply…


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. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: March 31, 2012
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.

Cats: Yay or nay?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read here first


How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

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