a^2-4a+9b^2+6b+5=0
a^2-4a+4+9b^2+6b+1=0
(a-2)^2+(3b+1)^2=0
a-2=0 a=2
3b+1=0 b=-1/3
a^2+2ab/ab-2b^2
=a(a+2b)/a(a-2b)
=(a+2b)/(a-2b)
=(2-2/3)/(2+2/3)
=6/8
=3/4
a^2-4a+9b^2+6b+5=0
a^2-4a+4+9b^2+6b+1=0
(a-2)^2+(3b+1)^2=0
a-2=0 a=2
3b+1=0 b=-1/3
a^2+2ab/ab-2b^2
=a(a+2b)/a(a-2b)
=(a+2b)/(a-2b)
=(2-2/3)/(2+2/3)
=6/8
=3/4