Answer:
z=(sqrt(10)-1)/2 or z= -(sqrt(10)-1)//2
Step-by-step explanation:
To complete the square, the last term has to be 1. So adding 10 to both sides, we get:
4z^2+4z+1 = 10
Since 4z^2+4z+1=(2z+1)^2,
(2z+1)^2 = 10.
Taking the square root of both sides, we get
2z+1=sqrt(10) or 2z+1=-sqrt(10)
So z=(sqrt(10)-1)/2 or z= -(sqrt(10)-1)//2
