SOLUTION: Write a polynomial function of minimum degree with real coefficients whose zeros include those listed. Write the polynomial in standard form. 7, -11, and 2 + 8i AND Stat

Algebra ->  Rational-functions -> SOLUTION: Write a polynomial function of minimum degree with real coefficients whose zeros include those listed. Write the polynomial in standard form. 7, -11, and 2 + 8i AND Stat      Log On


   



Question 765031: Write a polynomial function of minimum degree with real coefficients whose zeros include those listed. Write the polynomial in standard form.
7, -11, and 2 + 8i


AND
State how many imaginary and real zeros the function has.
f(x) = x^4 - 8x^3 + 17x^2 - 8x +16

Answer by DrBeeee(684) About Me  (Show Source):
You can put this solution on YOUR website!
All complex roots (zeroes) come in PAIRS. You need to include 2 - 8i as one of the four zeroes. Then we have the factored form of the polynomial is
(1) %28x-7%29%2A%28x%2B11%29%2A%28x-2%2B8i%29%2A%28x-2-8i%29
Just FOIL the first two factor and FOIL the last factors to get
(2) %28x%5E2%2B4x-77%29%2A%28x%5E2-4x%2B68%29
Now multiply the two quadratics of (2) and get
(3) x%5E4%2B0%2Ax%5E3-25x%5E2%2B580x-5207
This function (3) has two real zeroes, 7 and -11 and a complex pair of zeroes, 2+8i and 2-8i