SOLUTION: For the quadratic equation x^2 + kx +7 =0, if 3+sqrt2 is a root, what is the value of k ? I said 6 but my teacher marked it wrong. Please help me :)

Question 118532: For the quadratic equation x^2 + kx +7 =0, if 3+sqrt2 is a root, what is the value of k ?
I said 6 but my teacher marked it wrong. Please help me :)
Answer by tutor_paul(519) (Show Source): You can put this solution on YOUR website!
if something is a "root," it means it is a value for x which satisfies the equation. So plug the root in for x ans solve for k:

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