How can I solve for unknown variables in quadratic equation using excel?

[erickwy]

I am trying to solve for the quadratic equation in cell D40 with the unknown variable in cell D38 (where I gave an arbitrary number 10 here).

This picture is shown below.

I tried using solver add in software and the goal seek function in what-if analysis button but none of them worked to give out the desired two solutions.

I would greatly appreciate if I could get help on resolving this problem.
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