Solve for x in the equation x^2-4x-9=29? x=2+/- squareroot 42 x=2+/-squareroot 33 x=2+/-squareroot 34 x=4+/-squareroot 42

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))
 
 x = 2 +/- squareroot 42