想要更清晰地查看黑板内容，请查看每节课的 OCW Scholar 页面。这是这节课的页面：https://ocw.mit.edu/courses/mathematics/18-02sc-multivariable-calculus-fall-2010/2.-partial-derivatives/part-c-lagrange-multipliers-and-constrained-differentials/session-42-constrained-differentials/####[]