Question 229209: 2x^2-4x-1=0
answer: 2 + sqrt6 /2 , or 2 - sqrt6/2 anyone can give me a full break down of why trhe answer is 2 + sqrt 6/2 or 2 - sqrt6/2
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 2x^2-4x-1=0
This is a quadratic with a = 2 ; b = -4 ; and c = -1
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Use the Quadratic Formula:
x = [-b +- sqrt(b^2 - 4ac)]/(2a)
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Plug in the values for a, b, and c to get:
x = [4 +- sqrt(16 - 4*2*-1)]/4
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x = [4 +- sqrt(24)]/4
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x = [4 +- 2sqrt(6)]/4
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x = (1 + (1/2)sqrt(6)) or x = (1- (1/2)sqrt(6))
This can be written:
x = (2+sqrt(6))/2 or x = (2-sqrt(6))/2
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Cheers,
Stan H.
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