SOLUTION: Given -3x^2+9x+c=0 and the two roots sqrt( 2 ) and 3-sqrt( 2 ), find c.

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Question 370253: Given -3x^2+9x+c=0 and the two roots sqrt( 2 ) and 3-sqrt( 2 ), find c.
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Divide both sides by -3: x%5E2+-+3x-c%2F3+=+0. -c/3 is actually equal to the product of the roots. Hence %283%2Bsqrt%282%29%29%283-sqrt%282%29%29+=+9-2+=+7+=+-c%2F3. Thus c = -21.