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    Hi, got this question wrong but dont know what i did wrong. Please can you show me how its done? Thanks.

    Solve simultaneous equations:
    x+y=11
    xy=30

    PS i got x=17, y=-6 or x=16, y=-5
    When i sub it in it doesnt fit. Please help. It would be much appreciated.
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    (Original post by YsfAli)
    Hi, got this question wrong but dont know what i did wrong. Please can you show me how its done? Thanks.

    Solve simultaneous equations:
    x+y=11
    xy=30

    PS i got x=17, y=-6 or x=16, y=-5
    When i sub it in it doesnt fit. Please help. It would be much appreciated.
    Make x or y the subject of either equation, then substitute the result into the other one.

    Your solution only solves the first equation. Remember that both equations need to be satisfied simultaneously!
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    (Original post by YsfAli)
    Hi, got this question wrong but dont know what i did wrong. Please can you show me how its done? Thanks.

    Solve simultaneous equations:
    x+y=11
    xy=30

    PS i got x=17, y=-6 or x=16, y=-5
    When i sub it in it doesnt fit. Please help. It would be much appreciated.
    Post your working and we can tell you where you've gone wrong. :yy:
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    (Original post by YsfAli)
    Hi, got this question wrong but dont know what i did wrong. Please can you show me how its done? Thanks.

    Solve simultaneous equations:
    x+y=11
    xy=30

    PS i got x=17, y=-6 or x=16, y=-5
    When i sub it in it doesnt fit. Please help. It would be much appreciated.
    Truthfully, this is a ridiculously easy question that you can see the answer to without solving normally - just think about factors of 30.

    But for the actual method, just rearrange the first equation and substitute the result into the second.

    You'll find it makes a nice easy quadratic
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    It's 5 and 6


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