定义一种新算:a▲b=2a-b (1)直接写出b▲a的结果; (2)计算:【(X-2y)▲(X+y)]▲3y

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定义一种新算:a▲b=2a-b (1)直接写出b▲a的结果; (2)计算:【(X-2y)▲(X+y)]▲3y
定义一种新算:a▲b=2a-b (1)直接写出b▲a的结果; (2)计算:【(X-2y)▲(X+y)]▲3y

定义一种新算:a▲b=2a-b (1)直接写出b▲a的结果; (2)计算:【(X-2y)▲(X+y)]▲3y
a▲b=2a-b (1)b▲a= 2b-a
【(X-2y)▲(X+y)]▲3y
=[2X-4y-X-y]▲3y
=[X-5y]▲3y
=2X-10y-3y
=2X-13Y

b▲a=2b-a
【(X-2y)▲(X+y)]▲3y
先算中括号里面的
【(X-2y)▲(X+y)]=2(x-2y)-x-y=x-5y
【(X-2y)▲(X+y)]▲3y
=(x-5y)▲3y
=2(x-5y)-3y
=2x-13y