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    I'm doing simultaneous equations and I've got to (2y-12)(y+2), how do I work out y at this point?
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    (Original post by lemo****69)
    I'm doing simultaneous equations and I've got to (2y-12)(y+2), how do I work out y at this point?
    You can't, the quadratic not equal to anything.
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    (Original post by lemo****69)
    I'm doing simultaneous equations and I've got to (2y-12)(y+2), how do I work out y at this point?
    Hi please post the original question, thanks!
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    Is the quadratic you have there equal to 0?
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    Please Post the original question.
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    (Original post by lemo****69)
    I'm doing simultaneous equations and I've got to (2y-12)(y+2), how do I work out y at this point?
    Make sure you write down that it's equal to zero.
    (2y-12)(y+2) = 0

    2y = 12
    y = 6

    or

    y = -2

    So the answer is y = 6, y = -2
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    x+y = 4
    x*2+y*2 = 40
    solve this

    I substituted y into it so I had:
    2y*2-8y+16 = 40
    2y*2-8y-24 = 0

    I factorised and got:
    (2y-12)(y+4)
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    (Original post by Namita Gurung)
    Make sure you write down that it's equal to zero.
    (2y-12)(y+2) = 0

    2y = 12
    y = 6

    or

    y = -2

    So the answer is y = 6, y = -2
    Thanks!
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    (Original post by lemo****69)
    x+y = 4
    x*2+y*2 = 40
    solve this

    I substituted y into it so I had:
    2y*2-8y+16 = 40
    2y*2-8y-24 = 0

    I factorised and got:
    (2y-12)(y+4)
    (2y-12)(y+4) = 0

    So you know for that to be true, one (or both) of those brackets must equal zero.

    2y -12 = 0
    Y + 4 = 0

    Can you take it from here?
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    (Original post by lemo****69)
    x+y = 4
    x*2+y*2 = 40
    solve this

    I substituted y into it so I had:
    2y*2-8y+16 = 40
    2y*2-8y-24 = 0

    I factorised and got:
    (2y-12)(y+4)
    Yep that's correct
    (Original post by lemo****69)
    Thanks!
    You're welcome
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    (Original post by JLegion)
    (2y-12)(y+4) = 0

    So you know for that to be true, one (or both) of those brackets must equal zero.

    2y -12 = 0
    Y + 4 = 0

    Can you take it from here?
    Yeah, realised it had to be equal to 0 so I'd substitute 6 and -2 into the original equation. Thanks for the help!
 
 
 
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