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Math Help - Solving coefficients

  1. #1
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    Solving coefficients

    Equations
    1. 10 = 121a+11b+c
    2. x = -b/2a
    3. 35 = -b^2/4a + c
    4. b = 4.8233-22a

    There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

    equation 3. c = 35 + b^2/4a

    10= 121a+11b+35+b^2/4a
    10=121a+53.0563-242a+35+ (9.6466-212.2252+484a^2 all over 4a)
    40a = 212.2252a-484a^2+140a+9.6466-212.2252a+484a^2
    40a=140a+9.6466
    100a= - 9.6466
    a = -0.096466
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by bubbles73 View Post
    Equations
    1. 10 = 121a+11b+c
    2. x = -b/2a
    3. 35 = -b^2/4a + c
    4. b = 4.8233-22a

    There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

    equation 3. c = 35 + b^2/4a

    10= 121a+11b+35+b^2/4a
    10=121a+53.0563-242a+35+ (9.6466-212.2252+484a^2 all over 4a) You multiplied 4.8233 by 2 instead of squaring it. Should be 23.26422289.
    40a = 212.2252a-484a^2+140a+9.6466-212.2252a+484a^2
    40a=140a+9.6466
    100a= - 9.6466
    a = -0.096466
    I tried finishing it out after correcting the mistake, but ended up with a = 1.488707008. There's a lot of numbers there. Could've gone wrong somewhere.
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  3. #3
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    Quote Originally Posted by bubbles73 View Post
    Equations
    1. 10 = 121a+11b+c
    2. x = -b/2a
    3. 35 = -b^2/4a + c
    4. b = 4.8233-22a

    There are 4 unknowns and 4 equations. After numerous attempts of trying to find a i could really use some help. The actual value of a is -0.233 or part there of. Here is my best attempt, i cant see where i went wrong.

    ..
    [1.] refers to equation #1.

    Here is what I did:

    1. [1.] - [3.] = [13] that eliminates the variable c

    2. Plug in the term for b from [4.] into the equation [13]. Calculate a = -0.2326422289

    3. Plug in this value into [4.]. Calculate b = 9.941429035

    4. Plug in the values of a and b into [2.]. Calculate x = 21.36634669

    5. Plug in the values of a and b into [1.]. Calculate c = -71.20600969

    Please check my arithmetic. I'm a master of desaster if I have to use such unusual numbers.
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