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maths question

  • 25-10-2004 5:33pm
    #1
    ublinina
    Closed Accounts Posts: 21 ✭


    Can anybody help with this leaving cert maths question. its algebra part c .

    The quadratic equation f(x) = ax^2+ bx +c is shown , where a>0 ( a diagram of a quadratic curve is shown with the curve touching the x axis at point p ).

    The curve touches the x-axis at the point p.

    Find the co-ordinates of the point p in terms of a and b .


Comments

  • #2
    sci0x
    Closed Accounts Posts: 2,319 ✭✭✭sci0x


    What year did it come up? Its hard to understand it when its laid out like that.


  • #3
    Adama
    Closed Accounts Posts: 10 ✭Adama


    Hey,

    It's quite simple but the question seems to be worded wrong. If the quad curve only touches the x-axis at 1 point (i.e. P) then c = 0, by definition of a quad curve. Then the point P is given by:

    P=(x,y)

    y = 0 ...as it is on the x-axis

    x =>
    If y=ax^2 + bx +c ...Remember f(x) is the same as y
    Then

    ax^2 + bx = 0 ... As y=0, and c=0

    Rearranging this with algebra you will get,

    x = -b/a

    So the point P is at (-b/a , 0)

    Hope this helps.

    [EDIT] you know this answer seems right because it tells you a > 0, so this means the value -b/a can always to found! [EDIT]


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