Result x= 4 (D) and x = -3 (F). You should follow these steps:
X² + 4x - 9 = 5x +3 => X² + 4x - 5x - 9 = 3 => X² - x - 9 -3 = 0
Base on (a +b)² = a² + 2ab + b² and (a+b)² = value => a+b = +/- Value so
X² - x - 9 -3 = 0 => X² - x - 12 = 0 => X² - 2x.1/2 + 1/2² - 1/2² - 12 = 0
(X -1/2)² - 1/4 - 12 = 0 => (X-1/2)² - 1/4 - 48/4 = 0 => (X-1/2)² = 49/4
(x-/12) = +/- 7/2 So x -1/2 = 7/2 or x -1/2 = -7/2
And result is x = 8/2 = 4 or x = -6/2 = -3
