Question

已知x分之一减y分之一等于3,则代数式x-2xy-y分之2x-14xy-2y的值为?

Answer 1

1/x-1/y=3

(y-x)/xy=3

y-x=3xy

x-y=-3xy

x-2xy-y分之2x-14xy-2y

=[2(x-y)-14xy]/[(x-y)-2xy]

=(-20xy)/(-5xy)

=4