X-Intercepts

Thank you CPhill! That helps a lot!

Lily

The x intercepts occur where y = 0    ....so....

 x^2 - 6x - 9   =  0      complete the square.....add 9 to both sides

x^2  - 6x  =   9            take 1/2 of 6  = 3......square this and add to both sides

x^2 - 6x +  9   = 9 + 9

x^2 - 6x +  9   = 18        factor the left side

(x - 3)^2  = 18               take the square root of both sides

x - 3   =  pos/neg sqrt(18)   =  pos/neg 3sqrt(2)

x - 3  =  pos/neg 3sqrt(2)         add 3 to both sides

x =   pos/neg 3sqrt(2)  + 3    

So   x =    3sqrt(2) +3         and x  =  -3sqrt(2)  +  3