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    the straight line L has the equation y=3x-1 and the curve C has equation y=(x+3)(x-1)

    a) sketch on the same axes the line L and the curve C showing the values of the intercepts on the x-axes and the y axes

    b)show that the x-coordinates of the points of interception of L and C satisfy the equation x^2-x-2=0

    c)hence find the coordinates of the points of interception of L and C


    I have done question a but I really am lost with question b as in class we haven't really done much on this and in the textbook and revision guide I can not seem to find anything explaining it. any help appreciated
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    (Original post by βradley)
    the straight line L has the equation y=3x-1 and the curve C has equation y=(x+3)(x-1)

    a) sketch on the same axes the line L and the curve C showing the values of the intercepts on the x-axes and the y axes

    b)show that the x-coordinates of the points of interception of L and C satisfy the equation x^2-x-2=0

    c)hence find the coordinates of the points of interception of L and C


    I have done question a but I really am lost with question b as in class we haven't really done much on this and in the textbook and revision guide I can not seem to find anything explaining it. any help appreciated
    If the question was, "Find the coordinates of intersection of L and C", would you be able to do it? How do you find the intersection of two lines/curves given their equations?

    Your question is basically the same, just in your working you should arrive at x^2-x-2=0.

    Post all your working/thoughts if you get stuck.
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    (Original post by βradley)
    the straight line L has the equation y=3x-1 and the curve C has equation y=(x+3)(x-1)

    a) sketch on the same axes the line L and the curve C showing the values of the intercepts on the x-axes and the y axes

    b)show that the x-coordinates of the points of interception of L and C satisfy the equation x^2-x-2=0

    c)hence find the coordinates of the points of interception of L and C


    I have done question a but I really am lost with question b as in class we haven't really done much on this and in the textbook and revision guide I can not seem to find anything explaining it. any help appreciated
    At intersections, the coordinates are the same. Since the y-coordinates are the same, you can equate them to each other and simplify.
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    Where they intercept, they must be equal to each other. Therefore you can set 3x-1 = (x+3)(x-1)
    Now try and manipulate that and see if you get the equation given in the question
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    The y coordinate of the points of intersection will be 3x-1 (because the points are on the line) AND (x+3)(x-1) because the points are on the curve). So, put those two expressions equal to each other, and see if you can end up with the equation they have given you.
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    This is what i have finished with. Thanks for the help let me know if anything isn't right
 
 
 
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