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How do set for -1?

  1. Mar 17, 2013 #1

    I would like to make the answer equal -1

    here's the formula:

    4.5(x) - 9(1-x)

    How do I set this to equal -1? (This isn't homework, I'm working out some poker math and am not very good at this type of thing.) I use a TI 83 calculator.
  2. jcsd
  3. Mar 17, 2013 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    It's the same as 4.5(x) - 9(1-x)+1 = 0

    Take a hint from me:
    If you want to learn math, set your calculator aside.
  4. Mar 18, 2013 #3


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    Staff Emeritus
    Science Advisor

    To "set" something to -1 means to write "= -1" at the end! So to "set" 4.5x- 9(1- x) to -1 is just to write 4.5x- 9(1- x)= -1. If you mean "find the value of x that makes this true", use the usual "rules" of algebra. First multiply out those parentheses:
    4.5x- 9+ 9x= -1
    Add the terms in x, 13.5x- 9= -1. Now add 9 to both sides, then divide both sides by 13.5.

    Using a calculator to do that is like using a calculator to add "1+ 1" (and I have seen people do that!).
  5. Mar 18, 2013 #4


    Staff: Mentor

    +1 to that!
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