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    The question is:
    Find an inequality for K in its simplest form such that the quadratic equation
    Kx^2-(2K+3)x+(K+2)=0 has 2 distinct solutions.

    the answer I got was:
    K>9/4

    But the real solution is
    K>-9/4

    Can someone please explain how the minus for the K is cancelled out but for -9/4 it isn't?
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    (Original post by Aksa09)
    The question is:
    Find an inequality for K in its simplest form such that the quadratic equation
    Kx^2-(2K+3)x+(K+2)=0 has 2 distinct solutions.

    the answer I got was:
    K>9/4

    But the real solution is
    K>-9/4

    Can someone please explain how the minus for the K is cancelled out but for -9/4 it isn't?
    does it have 2 distinct solution? i did this

    b²-4ac
    (2k+3)²-4*k*(k+2)>0
    (4k²+12k+9)-4k(k+2)>0
    4k²+12k+9-4k²-8k>0
    4k+9>0
    4k>-9
    k>-9/4
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    (Original post by Aksa09)
    The question is:
    Find an inequality for K in its simplest form such that the quadratic equation
    Kx^2-(2K+3)x+(K+2)=0 has 2 distinct solutions.

    the answer I got was:
    K>9/4

    But the real solution is
    K>-9/4

    Can someone please explain how the minus for the K is cancelled out but for -9/4 it isn't?
    I'm sorry, which minus sign are you referring to, if you post some working I can try to spot a mistake.
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    (Original post by thefatone)
    does it have 2 distinct solution? i did this

    b²-4ac
    (2k+3)²-4*k*(k+2)>0
    (4k²+12k+9)-4k(k+2)>0
    4k²+12k+9-4k²-8k>0
    4k+9>0
    4k>-9
    k>-9/4
    Thankyou.
    But I thought the value for B would be -2K+3 as the equation has a minus before it.
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    (Original post by Aksa09)
    Thankyou.
    But I thought the value for B would be -2K+3 as the equation has a minus before it.
    B is -(2k+3), or -2k-3, but not -2k+3. Then when you square a negative number, you can just square the positive (e.g. (-3)^2 = 3^2 = 9), so you can do (2k+3)^2 as it's simpler than (-2k-3)^2.
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    (Original post by HapaxOromenon)
    B is -(2k+3), or -2k-3, but not -2k+3. Then when you square a negative number, you can just square the positive (e.g. (-3)^2 = 3^2 = 9), so you can do (2k+3)^2 as it's simpler than (-2k-3)^2.
    Oh yes, got it. Thankyou so much
 
 
 

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