>>80
∂{(1/r)*(∂/∂θ)}/∂r
={∂(1/r)/∂r}*(∂/∂θ)+(1/r)*{∂(∂/∂θ)/∂r}
= -(1/r^2)*(∂/∂θ)+(1/r)*{∂(∂/∂θ)/∂r}

ここまでじゃん？