The solution is m=2.
(2) Substitute y=x+2m for y=x? +2x+m- 1, and the discriminant is equal to 0.
That is x+2m = x 2+2x+m- 1.
x^2+x-m- 1=0
a= 1,b= 1,c=m- 1
Substitute b 2-4ac = 0.
m=5/4