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Homework Help: Equations - Graphs

  1. Nov 3, 2009 #1
    1. The problem statement, all variables and given/known data

    I have been given this equation : 4/5 X 2^x
    I have drawn the graph.

    Now, I was asked to draw the graph of y = 8 – 2x by using the 1st equation above.

    Can you help me in doing so? I know that the 1st Co-ordinates is (0,8) how can I find the other co-ordinate to draw the line?
  2. jcsd
  3. Nov 3, 2009 #2
    There isn't any need to use that graph to graph y=8-2x. This is just a line. Plot two points. Then draw a line through them.

    Also, don't use X for multiplication. Ever. :)
  4. Nov 3, 2009 #3


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    Science Advisor
    Homework Helper
    Gold Member

    What you have written isn't an equation; there is no = sign. And it also isn't clear what it means. Is the X supposed to be multiplication? Is it supposed to be (4/5)2x? Where is the y?
  5. Nov 3, 2009 #4


    Staff: Mentor

    The only way this problem makes any sense is if the second equation is y = 8 - 2x. In that case, you can look at the graph of this equation as being some transformations of the graph of y = (4/5)2x.
  6. Nov 3, 2009 #5
    Sorry the 1st equation was y= (4/5)2^x

    The 1st Co-ordinates are (0,8) since the y-intercept is 8 but I don't know how to find the 2nd Coordinates (x,y)
  7. Nov 3, 2009 #6


    Staff: Mentor

    What about the second equation? Is it y = 8 - 2x or y = 8 - 2x?
  8. Nov 3, 2009 #7
    Good catch.
  9. Nov 3, 2009 #8
    The 2nd equation is y = 8 - 2x
  10. Nov 3, 2009 #9


    Staff: Mentor

    Then this problem makes no sense.
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