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What is the equation of the quadratic with a root of 1-8i?

a) "x^2 - 2x + 65 = 0"
b) "x^2 + 2x + 65 = 0"
c) "x^2 - 2x + 65 = 0"
d) "x^2 + 2x + 65 = 0"

User Aoakenfo
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1 Answer

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Final answer:

The equation of the quadratic with a root of 1-8i is "x^2 - 2x + 65 = 0" because complex roots come in conjugate pairs and the expansion of the factors results in this equation.

Step-by-step explanation:

The correct equation of the quadratic with a root of 1-8i relies on the fact that the complex roots of polynomials with real coefficients come in conjugate pairs. Thus, if 1-8i is a root, then its conjugate 1+8i is also a root. Using these roots, we can find the quadratic equation by setting up factors (x - (1 - 8i)) and (x - (1 + 8i)) and expanding them.



The factors multiply to x² - (1 + 8i)x - (1 - 8i)x + (1 - 8i)(1 + 8i) = x² - 2x + (1 - 64) = x² - 2x + 65. So the equation of the quadratic is x² - 2x + 65 = 0.

User Justi
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