lemma
proved
tactic proof
taylorWithinEval_one_univ
show as:
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formal statement (Lean)
616lemma taylorWithinEval_one_univ (H : ℝ → ℝ) (x : ℝ) :
617 taylorWithinEval H 1 Set.univ 0 x = H 0 + deriv H 0 * x := by
proof body
Tactic-mode proof.
618 have h := taylorWithinEval_succ_real H 0 0 x
619 -- simplify the Taylor term at order 1
620 have h' :
621 taylorWithinEval H 1 Set.univ 0 x = H 0 + x * deriv H 0 := by
622 simp [taylor_within_zero_eval, iteratedDerivWithin_univ, iteratedDerivWithin_one,
623 iteratedDeriv_one, derivWithin_univ, sub_eq_add_neg] at h
624 simpa [mul_comm] using h
625 simpa [mul_comm] using h'
626