4+12(x-y)+9 (x?
4+12(x-y)+9 (x-y)
4+12(x-y)+9(x-y) =2^2+2*2*[3(x-y)]+[3(x-y)] =[2+3(x-y)] =(3x-3y+2)
答:4-12(x-y)+9(x-y)^2 =2^2-2*2*3(x-y)+[3(x-y)]^2 =[2-3(x-y)]^2 =(2-3x+3y)^2详情>>
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