Question 1207661
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Be aware: the solution and the answer by @Theo are incorrect.


One can see it even with unarmed eye.  Indeed,  in  Theo's equation 


                2k^2 - 3k - 4 = 0


the leading coefficient  " 2 "  is positive,  while the constant term  " -4 "  is negative.
It implies that the roots of this equation must be with opposite signs;
while Theo gives both roots positive at the end of his solution,  which is wrong.