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Can someone help me with this question? (further maths) watch

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    The curve with equation y=ax^2+bx+c passes through the points P(2,6) and Q(3,16), and has a gradient of 7 at the point P. Find the values of the constants a, b, and c.

    Help would be much appreciated
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    When x = 2, what does y equal? So what must a2^2 + 2b + c equal?
    Similarly for x =3.
    Also, at x=2, what does dy/dx equal. So ...
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    (Original post by DFranklin)
    When x = 2, what does y equal? So what must a2^2 + 2b + c equal?
    Similarly for x =3.
    Also, at x=2, what does dy/dx equal. So ...
    I'm still quite confused :confused:
    I've worked out that 4a+2b+c=6 and 9a+3b+c=16 but now what? dy/dx when x=2 is 7 but I dont know what to do with that information
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    Well, if y = ax^2+bx+c, then what is dy/dx?
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    Differentiate the equation with the unknowns and sub in the appropriate 'x' value, what should that equal to?
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    (Original post by DFranklin)
    Well, if y = ax^2+bx+c, then what is dy/dx?
    so dy/dx=2ax+b, when x=2 dy/dx=4a+b so 4a+b=7 ???
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    Yes. So you now have 3 equations in 3 unknowns, which is enough to solve for a, b and c. (Start by noting that b = 7-4a, so you can replace b by (7-4a) in the two other equations).
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    (Original post by DFranklin)
    Yes. So you now have 3 equations in 3 unknowns, which is enough to solve for a, b and c. (Start by noting that b = 7-4a, so you can replace b by (7-4a) in the two other equations).
    Thankyou that makes a lot more sense now... I'm very new to a-level maths :P
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    (Original post by looloo59)
    (Original post by DFranklin)
    Yes. So you now have 3 equations in 3 unknowns, which is enough to solve for a, b and c. (Start by noting that b = 7-4a, so you can replace b by (7-4a) in the two other equations).
    Thankyou that makes a lot more sense now... I'm very new to a-level maths :P
    Okay.. so maybe not so much sense. I've got confused again :confused:
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    (Original post by looloo59)
    Okay.. so maybe not so much sense. I've got confused again :confused:
    which part?
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    :eek: Now secretly glad that i decided agaisnt choosing further maths....
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    (Original post by Pixie_95)
    :eek: Now secretly glad that i decided agaisnt choosing further maths....
    This question appears to be from C1, which is simply 'normal' maths and not further maths.
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    (Original post by Farhan.Hanif93)
    This question appears to be from C1, which is simply 'normal' maths and not further maths.
    :s: Oh..well now slightly regretting choosing maths, better start revising from now :cool:
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    Well I think I have an answer now... y=3x^2-5x+4
    still not convinced I'm right but atleast I've got somewhere with it

    And the questions was taken from a further maths paper
 
 
 
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