Question

已知A.B.X.Y是有理数.且(X-A)的绝对值+(Y+B)^2=0

Answer 1

|x-a|+(y-b)²=2

那么有x-a=0即x=a,y+b=0即y=-b

[(a²+ay-bx+b²)/(x+y)]/[(a²+ax+by-b²)/(a+b)]

=[(a²-ab-ab+b²)/(a-b)]/[(a²+a²-b²-b²)/(a+b)]

=[(a²-2ab+b²)/(a-b)]/[2(a²-b²)/(a+b)]

=[(a-b)²/(a-b)]/[2(a+b)(a-b)/(a+b)]

=(a-b)/[2(a-b)]

=1/2