X² - 6x - 40=0

Complete the square

Step-by-step explanation:

x^2 - 6x - 40 = 0 ... get the - 40 to the other side

x^2 - 6x = 40 ... now take half of ur x term (6) ... so its 3 ... then square it (3^2 = 9) ... now add 9 to both sides

x^2 - 6x + 9 = 40 + 9

(x - 3) (x - 3) = 49

(x - 3) ^2 = 49 ... take sqrt of both sides, eliminating the ^2

x - 3 = sqrt 49

x = 3 ( + - ) 7

x = 3 + 7 = 10 or x = 3 - 7 = - 4

so x = 10 or x = - 4