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How is this discriminant question 5k and not -3k? I am really confused. watch

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    Question is:

    The equation kx^2 + kx + 3 - k = 0, where k is a constant, has no real roots.

    a) Show that 5k^2 - 12k <0

    Here is my solution. As you can see, I get the answer of -3k^2 -12k when I take a=k, b=k, c=3-k (using ax^2 + bx +c).

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    (Original post by blobbybill)
    Question is:

    The equation kx^2 + kx + 3 - k = 0, where k is a constant, has no real roots.

    a) Show that 5k^2 - 12k <0

    Here is my solution. As you can see, I get the answer of -3k^2 -12k when I take a=k, b=k, c=3-k (using ax^2 + bx +c).

    Name:  IMG_20170112_163751.jpg
Views: 35
Size:  498.1 KB
    Check the expansion of brackets ie -4k x -k is ...
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