Find the constant k such that the quadratic 2x^2 + 3x + 8x - x^2 + 4x + k has a double root.
Simplify as
x^2 + 15x + k
Double Root means discriminant = 0
15^2 - 4 (1)(k) = 0
225 - 4k = 0
225 = 4k
k = 225 / 4
+1768 
