The answer is -6.
Explanation:
To find the sum of the roots of a quadratic equation, you must follow this formula s = -b/a.
1. Identify the values of a, b & c
x²+6x-16=0
a = 1
b = 6
c = -16
2. Substitute the values to the formula s = -b/a
s = -b/a
s = -6/1
s = -6