SOLUTION: For what values of k does the equation 2x squared + (1-k)x+8=0 have a double root? I have tried numerous ideas, but cannot figure this out.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: For what values of k does the equation 2x squared + (1-k)x+8=0 have a double root? I have tried numerous ideas, but cannot figure this out.      Log On


   

Question 111727: For what values of k does the equation 2x squared + (1-k)x+8=0 have a double root? I have tried numerous ideas, but cannot figure this out.
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
a double root means a perfect square

dividing by 2 gives x^2+((1-k)/2)x+4=0

taking the square roots of 4 leads us to (x+2)^2=x^2+4x+4 and (x-2)^2=x^2-4x+4

(1-k)/2=4 ___ 1-k=8

(1-k)/2=-4 ___ 1-k=-8