等式a^2+b^2-6a-8b+25=0可化为：
a²-6a+9+b²-8b+16=0
(a-3)²+(b-4)²=0
则可得：a-3=0,b-4=0
即：a=3,b=4
所以：
[1+ b/a - a/(a-b)] /[1 - b/a - a/(a+b)]
=[(a+b)/a - a/(a-b)]/[(a-b)/a - a/(a+b)]
=(a²-b² - a²)/[a(a-b)] ÷ (a²-b²-a²)/[a(a+b)]
=(-b²)/[a(a-b)] × a(a+b)/(-b²)
=(a+b)/(a-b)
=(3+4)/(3-4)
=-7