Question

已知x-y除以x+2y等于三分之一,求x-2y除以x+y的值

Answer 1

由x-y除以x+2y等于三分之一,得,

(x-y)/(x+2y)=1/3

3(x-y)=x+2y

3x-3y=x+2y,

3x-x=2y+3y

2x=5y

解得x=5y/2

所以求x-2y除以x+y

=(x-2y)/(x+y)

=(5y/2-2y)/(5y/2+y)

=(y/2)/(7y/2)

=1/7