English
The equality derivWithin (f + g) s x = derivWithin f s x + derivWithin g s x holds under differentiability within s.
Русский
Существование равенства derivWithin (f + g) s x = derivWithin f s x + derivWithin g s x при дифференцируемости внутри s.
LaTeX
$$$\text{DifferentiableWithinAt } f s x \land \text{DifferentiableWithinAt } g s x \Rightarrow \ derivWithin (f + g) s x = derivWithin f s x + derivWithin g s x$$$
Lean4
theorem hasDerivAtFilter_const_add_iff (c : F) : HasDerivAtFilter (c + f ·) f' x L ↔ HasDerivAtFilter f f' x L :=
hasFDerivAtFilter_const_add_iff c