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2022-09-07 21:34:13 +08:00 · 2022-09-07 21:34:13 +08:00 · a5b15fef87
commit a5b15fef87
parent 12d67021c9
1 changed files with 1 additions and 1 deletions
--- a/问题/等差数列.md
+++ b/问题/等差数列.md
@ -13,7 +13,7 @@ $$ a_n = a + (n-1)d \tag{等差数列通项公式} $$
 由等差数列通项公式可以得到以下公式：
-$$ n = \dfrac{a_n}{d} + 1 \tag{已知首项尾项及公差求项数}$$
+$$ n = \dfrac{a_n - a}{d} + 1 \tag{已知首项尾项及公差求项数}$$
 等差数列求和公式：