Square x plus 9x minus 1 equals zero root

Square x plus 9x minus 1 equals zero root

X square + 9x = 1
X square + 9x + 81 / 4 = 1 + 81 / 4
(x + 9 / 2) square = 85 / 4
X + 9 / 2 = ± root 85 / 2
X = - (9-radical 85) / 2, x = - (9 + radical 85) / 2