Verified answer

1)D=(2b-1)²-4(b²-1)=0

4b²-4b+1-4b²+4=0

-4b+5=0

4b=5

b=5/4=1,25

2)b²-1=0

α)b=1 : (2-1)x+1=0, x+1=0, x=-1

β)b=-1: (-2-1)x+1=0, -3x+1=0,-3x=-1, x=1/3

Otvet: -1,1,5/4