Odredi sve trojke realnih brojeva (x,y,z)(x,y,z)(x,y,z) takve da vrijedi 1x+1y+z=13,1y+1z+x=15,1z+1x+y=17.\frac{1}{x} + \frac{1}{y + z} = \frac{1}{3}, \quad \frac{1}{y} + \frac{1}{z + x} = \frac{1}{5}, \quad \frac{1}{z} + \frac{1}{x + y} = \frac{1}{7}.x1+y+z1=31,y1+z+x1=51,z1+x+y1=71.