Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    I'm having difficulty with the following question:

    Solve the simultaneous equations
     4x^2 + y^2 = 10
     2x - y = 4

    The elimination method doesn't seem to work at all, and when I use the substitution method I get difficult numbers like  8x^2 = -6 or  3y^2 = -22 which can't be right. Any idea where I might be going wrong?

    Thanks in advance,

    Digichris.
    Offline

    0
    ReputationRep:
    (Original post by Digichris)
    I'm having difficulty with the following question:

    Solve the simultaneous equations
     4x^2 + y^2 = 10
     2x - y = 4

    The elimination method doesn't seem to work at all, and when I use the substitution method I get difficult numbers like  8x^2 = -6 or  3y^2 = -22 which can't be right. Any idea where I might be going wrong?

    Thanks in advance,

    Digichris.
    Rearrange the second equation to make either x or y the subject, square it and sub it into the first equation to get either x or y. Once you know one variable, you can sub it back into the second equation to get the other.

    EDIT: you should get 2 sets of x and y values, with each x value having a corresponding y value.
    Offline

    0
    ReputationRep:
    show that y = 2x - 4, then sub that in the equation with 4x^2.....etc, get the value(s) for x then value(s) for y
    • Thread Starter
    Offline

    0
    ReputationRep:
    Heh, thank you. I just realised I was making a stupid mistake xD
    Offline

    0
    ReputationRep:
    (Original post by Digichris)
    Heh, thank you. I just realised I was making a stupid mistake xD
    cool
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: March 26, 2011
The home of Results and Clearing

2,767

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  2. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  3. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
Poll
How are you feeling about GCSE results day?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

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

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

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