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计算x-yx+y+y-zy+z+z-xz+x+(x-y)(y-z)(z-x)(x+y)(y+z)(z+x)=()A.-1B.0C.1D.2

题目详情

计算

x-y
x+y
+
y-z
y+z
+
z-x
z+x
+
(x-y)(y-z)(z-x)
(x+y)(y+z)(z+x)
=(  )

A. -1

B. 0

C. 1

D. 2

▼优质解答
答案和解析
x-y
x+y
+
y-z
y+z
+
z-x
z+x
+
(x-y)(y-z)(z-x)
(x+y)(y+z)(z+x)

=
(x-y)(y+z)(z+x)
(x+y)(y+z)(z+x)
+
(y-z)(x+y)(z+x)
(x+y)(y+z)(z+x)
+
(z-x)(x+y)(y+z)
(x+y)(y+z)(z+x)
+
(x-y)(y-z)(z-x)
(x+y)(y+z)(z+x)

=
(x-y)(y+z)(z+x)
(x+y)(y+z)(z+x)
+
(x-y)(y-z)(z-x)
(x+y)(y+z)(z+x)
+
(y-z)(x+y)(z+x)
(x+y)(y+z)(z+x)
+
(z-x)(x+y)(y+z)
(x+y)(y+z)(z+x)

=
2z(x-y)
(y+z)(z+x)
-
2z(x-y)
(y+z)(z+x)

=0.
故选B.