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急好的有赏分(a-b+c-d)(-a-b-c-d)(x+y-z)(x-y+z)-(x+y+z)(x-y-z)

题目详情
急 好的有赏分
(a-b+c-d)(-a-b-c-d)
(x+y-z)(x-y+z)-(x+y+z)(x-y-z)
▼优质解答
答案和解析
1 原式=[(-b-d)+(a+c)][(-b-d)-(a+c)]=(-b-d)^2-(a+c)^2=b^2+2bd+d^2-a^2-2ac-c^2
2 原式=[x+(y-z)][x-(y-z)]-[x+(y+z)][x-(y+z)]=x^2-(y-z)^2-x^2+(y+z)^2=(y+z)^2-(y-z)^2=(y^2+2yz+z^2)-(y^2-2yz+z^2)=4yz