Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    13
    ReputationRep:
    How can i solve this?
    x^2 + y^2 = 9
    x+ y = 2
    Offline

    8
    ReputationRep:
    When you have two simultaneous equations and one is linear / simpler than the other (does not contain any squared terms) you can solve them by substitution.

    Rearrange the simpler one to make x or y the subject, for example y = 2 - x (by subtracting x from both sides)

    Can you see how that will help with the substitution method?
    Offline

    20
    ReputationRep:
    (Original post by warmmuffin)
    How can i solve this?
    x^2 + y^2 = 9
    x+ y = 2
    Rearrange the bottom to get y = 2 - x, then substitute this into the top one.
    Solve the resulting equation for x and then find the values of y.
    Online

    19
    ReputationRep:
    (Original post by warmmuffin)
    How can i solve this?
    x^2 + y^2 = 9
    x+ y = 2
    One is a simultaneous equation, the other is a linear equation.
    What do you do, you rearrange the linear equation to get one of the values and substitute them into the simultaneous equation.

    x^2 + y^2 = 9
    x+ y = 2

    If I, change this into y = 2 - x.
    Therefore, substitute it into the linear equation and carry on, remember (2-x)^2 is not 4 - x^2, remember how to square something in brackets, looks like the difference of squares, but it is slightly different.


    Posted from TSR Mobile
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brexit voters: Do you stand by your vote?
    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
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.