Answers

2015-01-29T22:45:02+08:00
Your are given the equation 2x^2 - kx +50 = 0. Recall that the solution to the equation ax^2 +bx +c = 0 is x =  \frac{-b \pm  \sqrt{b^2-4ac} }{2a} ,
which is known as the quadratic formula.
Using this formula, where a = 2, b = -k, c= 50, we have
x = \frac{-(-k) \pm \sqrt{(-k)^2-4(2)(50)} }{2(2)} = \frac{k\pm \sqrt{k^2-400}}{4}= \frac{k \pm \sqrt{(k-20)(k+20)}}{4}
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