SOLUTION: Find k such that the equation x^2 - kx + 4 = 0 has a repeated real solution.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Find k such that the equation x^2 - kx + 4 = 0 has a repeated real solution.       Log On


   

Question 1208779:
Find k such that the equation x^2 - kx + 4 = 0 has a repeated real solution.



Answer by Shin123(626) About Me  (Show Source):
You can put this solution on YOUR website!
Note that a quadratic has a repeated root if and only if the discriminant of it is 0. The discriminant of this quadratic is k%5E2-4%281%29%284%29=k%5E2-16. Therefore, we must have k%5E2-16=0, so k=4 or k=-4. We can check that both of these indeed work, x%5E2%2B4x%2B4=%28x%2B2%29%5E2, and x%5E2-4x%2B4=%28x-2%29%5E2.