c. 1/(1+1) + 2/(2+1) + 3/(3+1) +...+ (75/76), un= n/(n+1) n = 75
75 Σ k/(k+1) k = 1
(4) a. uk = 4 - 2k k = (1,2,3,4,5) k =1 , uk = 2 k = 2 , uk = 0 k = 3, uk = -2 k = 4, uk = -4 k = 5 , uk = -6 jumlahkan semua = -10
b. uk = 1/(k+2) k = (1,2,..,10) k = 1 , uk = 1/3 k = 2 , uk = 1/4 nilai = 1/3 + 1/4 + 1/5 + ...+ 1/12 1/3 + 1/5 + 1/7 +1/9 +1/11 = 7/8 1/4 + 1/6 + 1/8 + 1/10 + 1/12 = 29/40 jumlah 7/8 + 29/40 = 64/40= 8/5
4c uk = k(k+1)(k+2) k = 1,2,3,4,5,6 k = 1, uk = 1(2)(3) = 6 k = 2 , uk = 2(3)(4)= 24 k = 3 ,uk= 3(4)(5) = 60 k = 4, uk = 4(5)(6)= 120 k= 5, uk = 5(6)(7) = 210 k = 6, uk = 6(7)(8)= 336 jumlahkan = 756
Verified answer
Jawab2) tiga suku berikutnya
1, 5, 9
(bertambah tetap 4)
1, 5, 9, (13), (17), (21)
b)
4, 16, 36, 64,..
(2²), (4²), (6²), (8²), (10²), (12²) , (14²)
= 4, 16, 36, 64, 100, 144, 196
(3)
a. 1+3+..+25 , un = 2n -1
25 = 2n -1
n = 13
13
Σ 2k- 1
k= 1
b. 2 + 4 +...50 , un= 2n
2n = 50
n= 25
25
Σ 2k
k= 1
c. 1/(1+1) + 2/(2+1) + 3/(3+1) +...+ (75/76), un= n/(n+1)
n = 75
75
Σ k/(k+1)
k = 1
(4)
a.
uk = 4 - 2k
k = (1,2,3,4,5)
k =1 , uk = 2
k = 2 , uk = 0
k = 3, uk = -2
k = 4, uk = -4
k = 5 , uk = -6
jumlahkan semua = -10
b.
uk = 1/(k+2)
k = (1,2,..,10)
k = 1 , uk = 1/3
k = 2 , uk = 1/4
nilai = 1/3 + 1/4 + 1/5 + ...+ 1/12
1/3 + 1/5 + 1/7 +1/9 +1/11 = 7/8
1/4 + 1/6 + 1/8 + 1/10 + 1/12 = 29/40
jumlah 7/8 + 29/40 = 64/40= 8/5
4c
uk = k(k+1)(k+2)
k = 1,2,3,4,5,6
k = 1, uk = 1(2)(3) = 6
k = 2 , uk = 2(3)(4)= 24
k = 3 ,uk= 3(4)(5) = 60
k = 4, uk = 4(5)(6)= 120
k= 5, uk = 5(6)(7) = 210
k = 6, uk = 6(7)(8)= 336
jumlahkan = 756