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Math Help - Value of B

  1. #1
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    Value of B

    If f(x) = 3x^2 -Bx + 4 and f(-1) = 12, what is the value of B?

    Must I plug -1 for x in the given trinomial?

    Why is 12 given as a result in terms of f(-1)?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by blueridge View Post
    If f(x) = 3x^2 -Bx + 4 and f(-1) = 12, what is the value of B?

    Must I plug -1 for x in the given trinomial?

    Why is 12 given as a result in terms of f(-1)?
    yes, plug in x = -1 in the function and equate it to 12 as directed. B will be the only unknown, just solve for it

    f(-1) = 12 means, when the input is -1 the output is 12
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  3. #3
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    ok

    What would be the purpose for solving for B in questions like this one?
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by blueridge View Post
    What would be the purpose for solving for B in questions like this one?
    well, there are times when you want to find a certain type of function that behaves a certain way for whatever reason, and so using a similar method to this, you can find such a function.

    let's say you want to find a cubic polynomial that will go through certain points. you could say that the polynomial is of the form y = ax^3 + bx^2 + cx + d, and use properties like these to find the particular function
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