SOLUTION: Find the value of "k" in this equation, if one solution is 1/2 x^2 - kx + 15 = 0

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Question 943231: Find the value of "k" in this equation, if one solution is 1/2
x^2 - kx + 15 = 0

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
General solution for a quadratic equation,
x=%28k%2B-+sqrt%28k%5E2-4%2A15%29%29%2F2
x=%28k%2B-+sqrt%28k%5E2-60%29%29%2F2

Taking a guess that the plus-square root will work,
%28k%2Bsqrt%28k%5E2-60%29%29%2F2=1%2F2
k%2Bsqrt%28k%5E2-60%29=1
sqrt%28k%5E2-60%29=1-k
k%5E2-60=1-2k%2Bk%5E2
-60=1-2k
60=2k-1
59=2k
k=59%2F2
highlight%28k=29%261%2F2%29