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AS level Maths HELP!!! watch

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    Sketch the curve of f(x)=3x2-6x-7
    When you do the discriminant it gives you -50<0, thus meaning that there are no roots (doesn't cross the x-axis)
    But apprantly according to the textbook the roots are x=1+/-root(30)/3 (after completing the square)
    How is this possible is there are no roots???
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    (Original post by Anonymous)
    Sketch the curve of f(x)=3x2-6x-7
    When you do the discriminant it gives you -50<0, thus meaning that there are no roots (doesn't cross the x-axis)
    But apprantly according to the textbook the roots are x=1+/-root(30)/3 (after completing the square)
    How is this possible is there are no roots???
    a = 3
    b= -6
    c = -7

    b^2 = 36
    4ac =4 * 3 * -7 = -84

    b^2 - 4ac =
 
 
 
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