tentukan dalam bentuk sigma dari deret bilangan berikut : a. 1+4+9+16+25 b. 1+2+7+14+23 c. 1+5+9+13+17 d. 2+8+18+32+50

(a) 1 + 4 + 9 + 16 + 25 =
5 + 9 + 16 + 25 =
14 + 16 + 25 =
30 + 25 =
55

(b) 1 + 2 + 7+ 14 + 23 =
3 + 7 + 14 + 23 =
10 + 14 + 23 =
24 + 23 =
47

(c) 1 + 5 + 9 + 13 + 17 =
6 + 9 + 13 + 17 =
15 + 13 + 17 =
28 + 17 =
45

(d) 2 + 8 + 18 + 32 + 50 =
10 + 18 + 32 + 50 =
28 + 32 + 50 =
60 + 50 =
110