Question

已知：a方+b方-8a+6b+25=0,求a方+ab-6b方/a方-4ab+4b方 的值?

Answer 1

a^2+b^2-8a+6b+25=0

(a^2-8a+16)+(b^2+6b+9)=0

(a-4)^2+(b+3)^2=0

a=4

b=-3

(a^2+ab-6b^2)/(a^2-4ab+b)^2

=(a+3b)(a-2b)/(a-2b)^2

=(a+3b)/(a-2b)

=(4-12)/(4+6)

=-8/10

=-0.8