Question 320461
"Help please. I understand how to get the answers from quadratic equations. My problem is writing a quadratic equation from the solutions:  3+4i, 3-4i. This has me stumped."
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Quadratic Equation: ax^2 + bx + c = 0
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if solution is 3+4i:
3 + 4i - (3 + 4i) = 0
3 + 4i - 3 - 4i = 0
let's call this x - (3 + 4i) = 0
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if solution is 3-4i:
3 - 4i - (3 - 4i) = 0
3 - 4i - 3 + 4i = 0
let's call this x - (3 - 4i) = 0
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so then we have:
(x - (3 + 4i))(x - (3 - 4i)) = 0
we need to multiply this out using FOIL to get our quadratic equation
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x * x + x * -(3 - 4i) + x * -(3 + 4i) + (3 + 4i)(3 - 4i) = 0
x^2 + x * (4i - 3) + x * (-4i - 3) + 9 - 16i^2 = 0
x^2 + 4ix - 3x - 4ix - 3x + 9 + 16 = 0 (i^2 = -1)
x^2 - 6x + 25 = 0 (and this is your quadratic equation)