Answer:
x = - 2
Explanation:
f(x) + g(x) = x² - 2x + 6x + 4 = x² + 4x + 4, hence
x² + 4x + 4 = 0 ← This is a perfect square in the form
(x + a)² = x² + 2ax + a²
Hence 2a = 4 ⇒ a = 2, thus
(x + 2)² = 0
x+ 2 = 0 ⇒ x = - 2 ( 2 equal roots )
Value of x = - 2