Diketahui barisan :
7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, …
Soal :
Berdasarkan barisan diatas, hitunglah deret untuk 25 angka pertama !
✎ Rūles Mēnjawab :
⸙ Memakai cara penyelesaian
⸙ Rapi
⸙ Tidak ngasal
⸙ Good luck .-.
7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, …
- a = 7
- b = 11 - 9 = 2
- Suku ke-25
U25 = 7 + (25 - 1) × 2
U25 = 7 + 24 × 2
U25 = 7 + 48
U25 = 55
- Jumlah 25 suku pertama
[tex] \tt S_{25}= \frac{25}{2} \times (7 + 55)[/tex]
[tex]\tt S_{25}= \frac{25}{ \not2} \times\cancel{62} \:^{31}[/tex]
[tex]\tt S_{25}=25 \times 31[/tex]
[tex]\tt S_{25}=775[/tex]
[tex] \\ [/tex]
[tex]\bold{\mathbb{\color{ff0000}{♡} \color{ff4000}{♡}\color{ff8000}{♡}\color {ffc000}{♡}\color{ffff00}{♡}\color{c0ff00}{♡}\color {80ff00}{♡}\color{40ff00}{♡}\color {00ff00}{♡}\color{00ff40}{A}\color{00ff80}{N}\color {00ffc0}{N}\color{00ffff}{A}\color {00c0ff}{F}\color{0080ff}{A}\color{0040ff}{}\color {0000ff}{♡}\color{4000ff}{♡}\color{8000ff}{♡}\color{c000ff}{♡}\color{ff00ff}{♡}\color {ff00c0}{♡}\color{ff00a0}{♡}\color{ff0080}{♡}\color{ff0040}{♡}}}[/tex]
Mencari U25
=> 7 + 25 - 1 ) × 2
=> 7 + 24 × 2
=> 7 + 48
U25 => 55
=> 25/2 × ( 7 + 55 )
=> 25 × 31
=> 775
[tex] \: [/tex]
[answer.2.content]
