For this case what we must do is to use the formula of the resolvent in the following way:
x = (- b +/- root (b ^ 2 - 4 * a * c)) / (2 * a)
Where,
a = 1
b = -4
c = -38
Substituting the values:
x = (- (- 4) +/- root ((- 4) ^ 2 - 4 * 1 * (- 38))) / (2 * 1)
x = (4 +/- root (168)) / 2
x = (2 +/- root (42))
Answer:
x = 2 +/- squareroot 42
