Answer:
x = - 2
Explanation:
The problem might be easier if you wrote what (f + g)(x) means.
f(x) + g(x) = 0 is what the equations means from which you get.
x^2 - 2x + 6x + 4 = 0
x^2 + 4x + 4 = 0 This factors into
(x + 2)^2 = 0
Take the square root of both sides.
sqrt(x+2)^2 = sqrt(0)
x + 2 = 0
x = - 2