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Math Help - Linear functions

  1. #1
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    Linear functions

    Find a linear function g(x) where g(4)= -1. g(x) is parallel to the line f(x) = 3x+7
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  2. #2
    MHF Contributor red_dog's Avatar
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    g(x)=ax+b

    g(4)=-1\Rightarrow 4a+b=-1

    The graph of g is parallel to the graph of f, then a=3.

    Now find b.
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  3. #3
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    I'm still a little confused on how to solve for b.
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  4. #4
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    You can use the point-slope formula to solve this one too. You must be covering point-slope formula in your book at the moment, eh?

    You have been given a point and the slope of the line. They're not given explicitly, but you do have all the information you need. If you have a given line, and you know a second line is parallel to this line, then you know the slope of the second line. (Why?)

    Using the point you are given, and the slope, use the (what I am sure must be familiar to you by now) point-slope formula:

     y-y_1 = m(x - x_1)
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  5. #5
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    red dog told you: "g(x)= ax+ b" (the general form of any linear equation) , "g(4)= 4a+ b= 1 (you were given that), and "a= 3" (because wo parallel lines have the same slope).

    Replace the a in the 4a+ b= 1 by 2: 4(3)+ b= 12+ b= 1. Can you solve 12+ b= 1 for b?
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