Suppose the real numbers satisfy the following set of five equations:
Determine all the possible values that the number can take.
Solution
Suppose the real numbers satisfy the given set of equations. Let . Then, each of the five numbers satisfies the quadratic equation . This equation has 2 distinct real roots . Denote one of the roots equaling by and the other by . Then we have . Furthermore, if we assume that exactly among the numbers equal , and among them equal , we get . Substituting this into the equation , we obtain . Since , we must have either or . If we have , then we get , while if , we get . It is easy to check that each of these values of and the corresponding values for satisfy the quadratic equation , so the desired solution for the problem is given by .
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