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    Hey dont know what i got wrong but when i substitute to check if the set of values are right it is wrong the the second equation but right for the first.
    Simultaneous equations:
    2u+v=7
    uv=6

    v=7-2u
    u(7-2u)=6
    7u-2u^2=6
    -2u^2+7u-6=0
    (u+4)(u+3)=0
    u=-4 and u=-3

    sub into eq 3: v=7-2(-4)
    v=15

    sub other value: v=7-2(-3)
    v=13

    Values are: v=15 u=-4
    or v=13 u=-3

    What did i do wrong this time? Please help thanks.
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    (Original post by YsfAli)
    Hey dont know what i got wrong but when i substitute to check if the set of values are right it is wrong the the second equation but right for the first.
    Simultaneous equations:
    2u+v=7
    uv=6

    v=7-2u
    u(7-2u)=6
    7u-2u^2=6
    -2u^2+7u-6=0
    (u+4)(u+3)=0
    u=-4 and u=-3

    sub into eq 3: v=7-2(-4)
    v=15

    sub other value: v=7-2(-3)
    v=13

    Values are: v=15 u=-4
    or v=13 u=-3

    What did i do wrong this time? Please help thanks.

    Pretty sure it was the error in factorizing that cause this mistake
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    (Original post by YsfAli)
    Hey dont know what i got wrong but when i substitute to check if the set of values are right it is wrong the the second equation but right for the first.
    Simultaneous equations:
    2u+v=7
    uv=6

    v=7-2u
    u(7-2u)=6
    7u-2u^2=6
    -2u^2+7u-6=0
    (u+4)(u+3)=0
    u=-4 and u=-3

    sub into eq 3: v=7-2(-4)
    v=15

    sub other value: v=7-2(-3)
    v=13

    Values are: v=15 u=-4
    or v=13 u=-3

    What did i do wrong this time? Please help thanks.
    Just an error factorising. I would move the 7u-2u^2 to the other side personally, just makes it easier having a positive term first. Then it factorises to (2u-3)(u-2)=0.
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    2u^2-7u+6=0

    becomes

    2u^2-4u-3u+6=0

    therefore

    2u(u-2)-3(u-2)

    which is same as saying

    (2u-3)(u-2)

    So..

    u=3/2 or u=2
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    (Original post by mariaaax)
    2u^2-7u+6=0

    becomes

    2u^2-4u-3u+6=0

    therefore

    2u(u-2)-3(u-2)

    which is same as saying

    (2u-3)(u-2)

    So..

    u=3/2 or u=2
    Thank you so much i need to wake up !! lol
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    (Original post by YsfAli)
    Thank you so much i need to wake up !! lol
    Anytime
 
 
 

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