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algebra intermediate

Problem

Let be positive real numbers such that both and are both squares of polynomials. Find
Solution
If is the square of a polynomial, then it must be quadratic. We can assume that the quadratic is monic. Then to get a term of when we square it, the coefficient of in the quadratic must be Hence, Expanding, we get Matching coefficients, we get Similarly, if is the square of a polynomial, then we can assume the polynomial is of the form Hence, Expanding, we get Matching coefficients, we get From the equations and Thus, we can write Since either or If then and Substituting for we get Then so Then and

If then and Substituting for we get Then which has no real solutions.

Therefore, and so
Final answer
7