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If f(x) is a polynomial with real coefficients and zeros of 2 (multiplicity 3 ), -5 (multiplicity 3 ), -5+7i, and 2-4i, what is the minimum degree of f(x) ?

User Vine
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The minimum degree of the polynomial f(x) can be determined from its zeros and their multiplicities.

You mentioned that f(x) has zeros at:

1. 2 (multiplicity 3)

2. -5 (multiplicity 3)

3. -5 + 7i (which implies its conjugate -5 - 7i is also a zero)

4. 2 - 4i (which implies its conjugate 2 + 4i is also a zero)

To find the minimum degree of f(x), we need to consider the highest power of x that appears when you expand the polynomial with these zeros and their multiplicities.

For the zeros 2 (multiplicity 3) and -5 (multiplicity 3), we have factors of (x - 2)³ and (x + 5)³, respectively.

For the zeros -5 + 7i and its conjugate -5 - 7i, we have factors of (x - (-5 + 7i))(x - (-5 - 7i)) = (x + 5 - 7i)(x + 5 + 7i), which multiply out to a quadratic term.

For the zeros 2 - 4i and its conjugate 2 + 4i, we have factors of (x - (2 - 4i))(x - (2 + 4i)) = (x - 2 + 4i)(x - 2 - 4i), which also multiply out to a quadratic term.

So, the minimum degree of f(x) will be the sum of the exponents of the highest power terms from these factors:

Minimum degree = 3 + 3 + 2 + 2 = 10

Therefore, the minimum degree of f(x) is 10.

User Aaron J Lang
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