Find the constant k such that the quadratic 2x^2 + 3x + 8x - x^2 + 4x + k has a double root.
\(x^2 + 15x + k = 0\)
\(\Delta = \sqrt{225-4k} = 0\)
\(225-4k = 0\)
\(4k = 225\)
\(k = \frac{225}{4}\)
+864 
