m+2n分之2m-n的绝对值=3,求m+2n分之2(2m-n)-m+2n分之2m-n-3的值

∣(2m-n)/(m+2n)∣=3
(2m-n)/(m+2n)=±3
当(2m-n)/(m+2n)=3时
∣2(2m-n)/(m+2n)∣-(2m-n)/(m+2n)-3
=2∣(2m-n)/(m+2n)∣-(2m-n)/(m+2n)-3
=2*3-3-3
=0
当(2m-n)/(m+2n)=-3时
∣2(2m-n)/(m+2n)∣-(2m-n)/(m+2n)-3
=2∣(2m-n)/(m+2n)∣-(2m-n)/(m+2n)-3
=2*3-(-3)-3
=6+3-3
=6