English
If f and g are differentiable on a set s, then f − g is differentiable on s.
Русский
Если функции f и g дифференцируемы на s, то f − g дифференцируема на s.
LaTeX
$$$\\text{DifferentiableOn}_{\\mathbb{k}}(f, s) \\land \\text{DifferentiableOn}_{\\mathbb{k}}(g, s) \\Rightarrow \\text{DifferentiableOn}_{\\mathbb{k}}(f - g, s)$$$
Lean4
@[fun_prop]
theorem sub (hf : DifferentiableOn 𝕜 f s) (hg : DifferentiableOn 𝕜 g s) : DifferentiableOn 𝕜 (f - g) s := fun x hx =>
(hf x hx).sub (hg x hx)