Question

已知x2-5xy=0(y≠0),求x-y/x+y的值

Answer 1

x^2-5xy=0

x(x-5y)=0

x=0或x=5y

将x=0代入(x-y)/(x+y)得

(0-y)/(0+y)

=-y/y

=-1

将x=5y代入(x-y)/(x+y)得

(5y-y)/(5y+y)

=4y/6y

=2/3