Respuesta :

Take a factor of 5 out to get;
Y=5(x^2-4x-(9/5))
Then to complete the square you have to (x+half the number in front of x)^2 -c
In this case:
Y=5((x-2)^2 -4-9/5))
Y=5((x-2)^2 -29/5)
Y=5(x-2)^2 -29

(Then solve for y=0)