If 1x+1y=1z\frac{1}{x} + \frac{1}{y} = \frac{1}{z}x1+y1=z1, which of the following is equivalent to xxx?
yzy−z\frac{yz}{y-z}y−zyz
yzz−y\frac{yz}{z-y}z−yyz
y−zyz\frac{y-z}{yz}yzy−z
y−zy-zy−z