Do anybody know how to slove x to the 2nd piwer + 15x - 54=

X² + 15x - 54 = 0

x = - (15) + / - √ ((15) ² - 4 (1) (-54))

2 (1)

x = - 15 + / - √ (225 + 216)

2

x = - 15 + / - √ (441)

2

x = - 15 + / - 21

2

x = - 15 + 21 or x = - 15 - 21

2 2

x = 6 x = - 36

2 2

x = 3 x = - 18