Tolong bantu kak matématika pola bilangan beserta caranya makasih
Penjelasan dengan langkah-langkah:
1.
5 , 9 , 13 , 17
b = U3-U2 = U2-U1
b = 13-9 = 9-5
b = 4 = 4
b = 4
a.
Un = a+(n-1) b
U25 = 5+(25-1) 4
U25 = 5+24×4
U25 = 5+96 = 101
b.
Sn = n/2 (2a+(n-1) b )
S13 = 13/2 (2(5) + (13-1) 4
S13 = 13/2 x (10 + 12 x4)
S13 = 13/2 x (10 + 12 x 4)
S13 = 13/2 x 58
S13 = 13 x 29
S13 = 377
2.
U5 = 21
U8 = 36
a+7b = 36
a+4b = 21
________ –
3b = 15
b = 15/3
b = 5
Cari nilai a(U1)
a+4b = 21
a+4(5) = 21
a+20 = 21
a = 21-20
a = 1
Un = a+(n-1) b
U20 = 1+(20-1) 5
U20 = 1+19×5
U20 = 1+95
U20 = 96