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Math Help - help with finding constants in quadratice function

  1. #1
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    help with finding constants in quadratice function

    This is the problem I'm having trouble with right now and its racking my brain, any help would be appreciated:

    Consider a quadratic function Q(y)=A⁢y2+B⁢y+C. If Q(2)=0, Q(3)=0 and Q(1)=-4, find C the constant term in Q.
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  2. #2
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    Quote Originally Posted by forkball42 View Post
    This is the problem I'm having trouble with right now and its racking my brain, any help would be appreciated:

    Consider a quadratic function Q(y)=A⁢y2+B⁢y+C. If Q(2)=0, Q(3)=0 and Q(1)=-4, find C the constant term in Q.
    What are those boxes (⁢)? Your question appears is appearing as Q(y)=A⁢y2+B⁢y+C. Is it Q(y) = Ay^2 + By + C?

    For this question, substitute y=2, 3, 1 and you will get three equation which you can use simultaneous equation technique to work out constant value of A, B and C.
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  3. #3
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    Quote Originally Posted by forkball42 View Post
    This is the problem I'm having trouble with right now and its racking my brain, any help would be appreciated:

    Consider a quadratic function Q(y)=A⁢y2+B⁢y+C. If Q(2)=0, Q(3)=0 and Q(1)=-4, find C the constant term in Q.
    Q(y)=Ay^2+By+C

    for Q(2)=0,

    0=A(2)^2+B(2)+C

    4A + 2B + C =0 .......................................eqn. (1)

    for Q(3)=0,

    9A + 3B + C = 0 ..................................... eqn.(2)

    for Q(1) = - 4,

    A + B + C = - 4 .......................................eqn.(3)

    subtract eqn(3) from eqn(1) and eqn (2), we get:

    3A + B = 4 ............................................EQN(4)

    and 8A + 2B =4
    or,
    4A + B =2 ..........................................EQN(5)

    Solve EQN(4) AND EQN(5):
    we get:
    A = - 2, B = 10
    Put these values in eqn(3), we got C = - 12
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