--- a/src/HOL/Analysis/ex/Approximations.thy Thu Aug 27 16:48:21 2020 +0100
+++ b/src/HOL/Analysis/ex/Approximations.thy Fri Aug 28 12:04:36 2020 +0100
@@ -99,9 +99,8 @@
from assms show "(exp x - approx) \<ge> 0"
by (intro sums_le[OF _ sums_zero sums]) auto
- have "\<forall>k. x^n * (x^k / fact (n+k)) \<le> (x^n / fact n) * (x / 2)^k"
- proof
- fix k :: nat
+ have "x^n * (x^k / fact (n+k)) \<le> (x^n / fact n) * (x / 2)^k" for k::nat
+ proof -
have "x^n * (x^k / fact (n + k)) = x^(n+k) / fact (n + k)" by (simp add: power_add)
also from assms have "\<dots> \<le> x^(n+k) / (2^k * fact n)"
by (intro divide_left_mono two_power_fact_le_fact zero_le_power) simp_all