What is the polynomial function of lowest degree with rational real coefficients, and roots -3 and square root of 6?

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  f(x) = x³ +3x² -6x -18

Step-by-step explanation:

In order for there to be a root of √6, there must be a factor of (x-√6). In order for there to be rational coefficients, there needs to be another factor of (x+√6) in the minimal polynomial. Then the minimal polynomial with the required roots is ...

  f(x) = (x +3)(x -√6)(x +√6) = (x +3)(x² -6)

  f(x) = x³ +3x² -6x -18