我们还学过微分的链式法则，也就是用其他量来代替这些偏导数。

So, we've learned about differentials and chain rules, which are a way of repackaging these partial derivatives.

youdao

我们可以从限制条件中找到这个，我们一开始就看到的，要么用微分限制条件，要么利用链式法则。

OK, and we can find this one from the constraints as we've een at the beginning either by differentiating the constraint, or by using the chain rule on the constraint.

youdao

可以通过隐函数微分法和乘法法则得到，或者直接,把关于x，y，z的偏微分放进来。

You can get this either by implicit differentiation and the product rule, or you could get this just by putting here, here,and here the partial derivatives of this with respect to x, y, and z.

youdao