SOLUTION: Write a quadratic equation whose roots are 6+4i and 6-4i. My answer is x^2-12x+40=0 Is this correct?

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: Write a quadratic equation whose roots are 6+4i and 6-4i. My answer is x^2-12x+40=0 Is this correct?      Log On


   



Question 192529This question is from textbook saxon algebra 2
: Write a quadratic equation whose roots are 6+4i and 6-4i.
My answer is x^2-12x+40=0
Is this correct?
This question is from textbook saxon algebra 2

Found 3 solutions by stanbon, Earlsdon, solver91311:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Write a quadratic equation whose roots are 6+4i and 6-4i
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y = [(x-6)+4i] * [(x-6)-4i]
y = (x-6)^2 - (4i)^2
y = x^2 - 12x + 36 + 16
y = x^2 -12x + 52
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Cheers,
Stan H.

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Find the quadratic equation whose roots are:
x+=+%286%2B4i%29 and x+=+%286-4i%29
If these are the roots, then the factors of the equation are:
x-%286%2B4i%29 and x-%286-4i%29
To find the equation with these factors, multiply the factors.
%28x-%286%2B4i%29%29%28x-%286-4i%29%29+=+highlight%28x%5E2+-12x+%2B52%29
One way you could have checked your answer would have been to solve your equation for x using the quadratic formula. Let's see what would we get:
x%5E2-12x%2B40+=+0
Use x+=+%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a and a = 1, b = -12, and c = 40.
x+=+%28-%28-12%29%2B-sqrt%28%28-12%29%5E2-4%281%29%2840%29%29%29%2F2%281%29
x+=+%2812%2B-sqrt%28144-160%29%29%2F2
x+=+%2812%2B-sqrt%28-16%29%29%2F2 or...
x+=+6%2B2i and x+=+6-2i Not quite the same as the given roots.

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


I suspect you used the correct process, but you have a little arithmetic problem.

The quadratic trinomial whose factors are x - (6 + 4i) and x - (6 - 4i) is:





Hence the desired equation is:



John