Tentukan rumus ke-N dri barisan bilangan berikut,kemudian tentukan U25=
1) 1,4,7,10....
2) 10,7,4,1.....
3) 0,7,14,21,28.....
Penjelasan dengan langkah-langkah:
nomor 1
jelas a = 1 dan b = 3
Un = 3n-2
[tex]u25 = a + (n - 1)b \\ = 1 + (25 - 1)3 \\ = 1 + 24 \times.3 \\ = 73[/tex]
nomor 2
jelas a = 10 dan b = -3
Un = -3n + 13
[tex]u25 = 10 + 24.( - 3) \\ = 10 + ( - 72) \\ = - 62[/tex]
nomor 3
a = 0 dan b = 7
Un = 7n - 7
[tex]u25 = 0 + 24.7 \\ = 168[/tex]
Jawab:
Penjelasan dengan langkah-langkah:
[tex]1) \; U = \{1,4,7,10,...\}= \{-2+3,-2+6,-2+9,-2+12,...\}\\U_n = -2+3n\to \boxed{\boxed{U_{25} =-2+75= 73 }}\\\\2) \; U = \{10,7,4,1,...\}= \{13-3,13-6,13-9,13-12,...\}\\\\U_n = 13-3n\to \boxed{\boxed{U_{25} =13-75= -62 }}\\\\2) \; U = \{0,7,14,21,28,...\}= \{7(1-1),7(2-1),7(3-1),7(4-1),...\}\\\\U_n = 7(n-1)\to \boxed{\boxed{U_{25} =7\cdot 24= 168 }}[/tex]
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