用动态和微观的观点理解微分学懂导数、偏导数,再学微分就简单多了。这些知识是相通的,基本不需重新理解,动态和微观的观点仍然通用。前面已经学过,导数的表达式是这样的: f ′ ( x ) = y ′ = d y d x = lim Δ x → 0 Δ y Δ x = lim Δ x → 0 d y + o ( x ) Δ x f'(x) = y' = \frac{dy}{dx} = \lim_{\Delta x \to 0}\frac{\Delta y}{\Delta x} = \lim_{\Delta x \to 0}\fr