Question

若X*X+Y*Y-4X+6Y+13=0,求X-Y 已知1/a-1/b=2求(2a-ab-2b)/(a+ab-b)

Answer 1

x²+y²-4x+6y+13=0

(x-2)²+(y+3)²=0

所以x-2=0 x=2

y+3=0 y=-3

x-y=2-(-3)=5

1/a-1/b=2

(b-a)/ab=2

a-b+2ab=0

a-b=-2ab

a-b+ab=-ab

2(a-b)-ab=-4ab-ab=-5ab

(2a-ab-2b)/(a+ab-b)=(-5ab)/(-ab)=5