已知(x+y+z)(x+y)(y+z)(z+x)不等于零
且[x^2/(y+z)]+[y^2/(z+x)]+[z^2/(x+y)]=0
求:
1. [x/(y+z)] + [y/(z+x)] + [z/(x+y)] = ?
2. [x^2/(yz)] + [y^2/(zx)] + [z^2/(xy)] = ?
感激不尽！

没有附想法, 警告一次