Question

已知x分之一减y分之一等于五,求分式2x+7xy—2y分之-x+xy+y的值

Answer 1

1/X-1/Y=5,

去分母得：Y-X=5XY,

2x+7xy—2y分之-x+xy+y

=[(y-x)+xy]/[-2(y-x)+7xy]

=6xy/(-3xy)

=-2.