Question

蛞蝓

2的Ｋ次方連加是怎麼變到下一個式子的？

整數
3
a均成立
1=0
-=-日
E
20
20
= E3k- Σ1=3Σk - Σ1
k = 1
k = 1
k = 1
=3(1+2+3++20)-1×20
= 3 ×
20
k = 1
20 × 21
2
10
(2) Σ (3 × 2 + 1)
k = 1
= 3 ×
10
10
10
=
- Σ (3 x 2) + 1 =3Σ2 +
k = 1
k = 1
k = 1
2(20-1
2-1
20
-20 630-20=610
= 3 (2+22² +2³+...+2¹0) + 1 × 10
=3(2+2+2+…
20
(3) Σ (6k-7)
k = 11
20
H
+ 10
= 3 x 2 x (1024-1)+10=6148
20
10
=
= Σ (6k-7) - Σ (6k-7)
k = 1
k = 1
10
Σ1
k = 1
10
10
= (6Ë k- £7)-(62 k- [7)
k =
k = 1
k = 1
k = 1

求級數和

Answer 1

特拉瓦

這是等比級數的公式⋯⋯

蛞蝓

哦對耶謝謝！(⁎⁍̴̛ᴗ⁍̴̛⁎)