z/x=z/uu/x+z/vv/x=2ulnv×1+u²/v×2xy=2(x+y)ln(x²y)+2(x+y)²/xz/y=z/uu/y+z/vv/y=2ulnv×1+u²/v×x²=2（x+y）ln(x²y)+(x+y)²/y
