If a,b,c,d are rational numbers(有理数),|a-b|≤9,|c—d|≤16 and |a-b-c+d|=25

问题描述:

If a,b,c,d are rational numbers(有理数),|a-b|≤9,|c—d|≤16 and |a-b-c+d|=25
If a,b,c,d are rational numbers(有理数),|a-b|≤9,|c—d|≤16 and |a-b-c+d|=25,then |b-a|-|d—c|= .

|a-b|+|c-d|≤9+16=25,而|a-b|+|c-d|≥|a-b-c+d|=25,又|a-b|≤9,|c-d|≤16,所以|a-b|=9,|c-d|=16,则|b-a|-|d-c|=-7