Which of the following is equal to (z+1/z)2-(z-1/z)2?

1.	Which of the following is equal to (z+1/z)2-(z-1/z)2?
A.	0
B.	4
C.	1/z2-z2
D.	2/z2-2z2
Answer» C. 1/z2-z2

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