B步骤错了
错误的原因是分母不一样,不能合并
3x/(x-4y)+(x+y)/(4y-x)-17y/(x-4y)
=3x/(x-4y)-(x+y)/(x-4y)-17y/(x-4y)
=(3x-x-y-17y)/(x-4y)
=(2x-18y)/(x-4y)
B步骤错了
错误的原因是分母不一样,不能合并
3x/(x-4y)+(x+y)/(4y-x)-17y/(x-4y)
=3x/(x-4y)-(x+y)/(x-4y)-17y/(x-4y)
=(3x-x-y-17y)/(x-4y)
=(2x-18y)/(x-4y)