大家帮我看一个，这个求偏导的题答案是不是错了

好像是错了，把结果中的2yf''(2)改为2yf'(2)

z=f(xy²,x²y)
另xy²=u,x²y=v u'(x)=y² v'(x)=2xy
则z'(x)=f'(u)u'+f'(v)v'=f'(u)y²+f'(v)2xy
z''(xx)=f''(uu)u'y²+f''(uv)v'y²
+f''(vu)u'2xy+f''(vv)v'2xy+f'(v)2y
=f''(uu)y^4+f''(uv)2xy^3
+f''(vu) y²2xy+f''(vv)2xy2xy+f'(v)2y
=f''(uu)y^4+4xy^3f''(uv)+4x^2y^2f(vv) +2yf'(v)