-(x-y+1)乘以(x-y-1)怎么去括号

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-(x-y+1)乘以(x-y-1)怎么去括号

-(x-y+1)乘以(x-y-1)怎么去括号
-(x-y+1)乘以(x-y-1)怎么去括号

-(x-y+1)乘以(x-y-1)怎么去括号
这是个平方差
-(x-y+1)(x-y-1)
=-[x^2-(y-1)^2]
=(y-1)^2-x^2
=y^2-2y+1-x^2

原式=-[x-(y-1)][x+(y-1)]
=-[x²-(y-1)²]
=(y-1)²-x²
=y²-x²-2y+1

=-[(x-y)+1][(x-y)-1]
=-[(x-y)²-1]
=-(x²-2xy+y²-1)
=-x²+2xy-y²+1