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Homework Help: Can someone correct my questions and help me please.

  1. Jan 9, 2010 #1
    The line y = x + 2 intersects the curve 4y + 3x^2 = 7 in two places.

    a) Find the coordinates of the two points of intersections.

    >Sub. y = x + 2 to 4y + 3x^2 = 7
    >4(x+2) + 3x^2 = 7
    >4x + 8 + 3x^2 -7 = 0
    >3x^2 + 4x -1 = 0
    >x = -1 and - 1/3
    >y = x + 2
    >so y = 1 or 5/3

    The straight line y = f(x) has gradient 3 and intersects the curve 4y + 3x^2 = 7 at one point only.

    b) Find f(x).

    >???

    c) Hence find the coordinates of the point of intersection between y = f(x) and 4y + 3x^2 =7

    >???

    :(
     
  2. jcsd
  3. Jan 9, 2010 #2
    to question b)
    we know that y = f(x) has gradient 3, so y=3x+m, and 4y+3x^2=7
    >4(3x+m)+3x^2=7
    >3x^2+12x+4m-7=0
    at one point only, so the equation above has only one solution, Δ=0
    >m=17/4

    q c) is easy ^.^
     
  4. Jan 9, 2010 #3
    Thankyou Very Much!! ^^"
     
  5. Feb 17, 2010 #4
    i think that alright you aint to old or to young to learn more
     
  6. Feb 17, 2010 #5

    berkeman

    User Avatar

    Staff: Mentor

    Do NOT do the OP's work for them. They are required to do their own homework here at the PF.
     
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