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    Hello everyone,

    I'm having trouble with question 3c in the attachment - I have found when f(x) = x (x= -2 or 4/3 I think), but I don't get how to write the inequality bit? Do I write two inequalities or is only one of these values possible to use?
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    Add y = x to your graph and compare with y = f(x).

    If you know the intersections, the solution to the inequality is given where the function is lower than the y=x graph.
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    (Original post by Alexion)
    Add y = x to your graph and compare with y = f(x).

    If you know the intersections, the solution to the inequality is given where the function is lower than the y=x graph.
    So... f(x) < -2 ?
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    (Original post by Electrogeek)
    So... f(x) < -2 ?
    and...
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    (Original post by Alexion)
    and...
    f(x) < 4/3?
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    (Original post by Electrogeek)
    f(x) < 4/3?
    You actually want it in terms of x, not f(x), my bad

    so it's x < -2 and x > 4/3
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    (Original post by Alexion)
    You actually want it in terms of x, not f(x), my bad

    so it's x < -2 and x > 4/3
    Thanks! I think I get it now - so it was asking which values of x would give a value which is less than the points of intersection?.

    Also, if I'm told to deduce the number of roots of 2x+3=2x^2 (for example), is that the x-coordinates for the point(s) of intersection?
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    (Original post by Electrogeek)
    Also, if I'm told to deduce the number of roots of 2x+3=2x^2 (for example), is that the x-coordinates for the point(s) of intersection?
    The roots would be the points of intersection, yes.

    However, if a question simply asked you to deduce the number of roots, it would be 2; if you turned it into one function (= 0) then it'd be a quadratic (i.e. two roots). The other way would be to quickly sketch both graphs which would indicate both intersections.
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    (Original post by Alexion)
    The roots would be the points of intersection, yes.

    However, if a question simply asked you to deduce the number of roots, it would be 2; if you turned it into one function (= 0) then it'd be a quadratic (i.e. two roots). The other way would be to quickly sketch both graphs which would indicate both intersections.
    Cool - Thanks!
 
 
 
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