A={x/x^2+(a-1)x+b=0}={a},
a是x^2+(a-1)x+b=0的惟一解
△=(a-1)^2-4b=0
b=(a-1)^2/4
把x=a代入x^2+(a-1)x+(a-1)^2/4=0得:
a^2+(a-1)a+(a-1)^2/4=0
9a^2-6a+1=0
(3a-1)^2=0
a=1/3
b=(a-1)^2/4=(2/3)^2/4=1/9
a=1/3,b=1/9
a+b=1/3+1/9=4/9
A={x/x^2+(a-1)x+b=0}={a},
a是x^2+(a-1)x+b=0的惟一解
△=(a-1)^2-4b=0
b=(a-1)^2/4
把x=a代入x^2+(a-1)x+(a-1)^2/4=0得:
a^2+(a-1)a+(a-1)^2/4=0
9a^2-6a+1=0
(3a-1)^2=0
a=1/3
b=(a-1)^2/4=(2/3)^2/4=1/9
a=1/3,b=1/9
a+b=1/3+1/9=4/9