How to use Goal Seek?

How do I find the value of X to solve the equation? I have never used Goal Seek and I don't even know where to find it! If I could have a step by step walk through of how to do this that would be amazing!

(x^5) = (19) - (2x)

1 Answer

  • 9 years ago
    Favorite Answer

    Goal Seek is an algorithm implemented in certain software products such as Ms Excel and OpenOffice Calc.

    It uses numerical methods to find the argument for which a function value achieves a value provided by the user.

    To solve your equation: (x^5) = (19) - (2x), using this method, we proceed as follows.

    The equation is equivalent to: x^5 +2x -19=0.

    To find a root of this function, enter the following formula: "=A1^5+2*A1-19" in cell B1 of your spreadsheet. If you are using OpenOffice Calc, then you try "Tools, Goal Seek...". This will bring up a dialog box where you can enter the target value for your formula. The target value is 0. You also need to tell the spreadsheet program which cell contains the independent variable. In our example, this is cell A1.

    OpenOffice then says that it finds a root of the function at : x=1,731.

    Note: the Goal Seek algorithms have their limitations. Your equation is of the fifth degree. Now, the goal seek function only finds one root. There could be multiple roots (up to five), but some may remain hidden.

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