Tolong jawab pake cara
Diketahui suatu barisan aritmatika dengan suku pertamanya -15 dan suku kelimanya 1.
A.tentukan beda barisan aritmatika tersebut
B.tentukan suku kesepuluh barisan aritmatika tersebut
C.tuliskan 10 suku pertama barisan aritmatika tersebut
Buat master mtk
Diketahui:
a = -15 ————>> (1)
U5 = 1
a + 4b = 1 ————>> (2)
Jawab:
A).
Subtitusikan 1 dan 2,,
a + 4b = 1
-15 + 4b = 1
4b = 1 + 15
4b = 16
b = 16/4
b = 4
B). Masukkan nilai a dan b ke,,
= U10
= a + 9b
= -15 + 9(4)
= -15 + 36
= 21
C).
U1 = a = -15
U2 = a + b = -15 + 4 = -11
U3 = a + 2b = -15 + 2(4) = -7
U4 = a + 3b = -15 + 3(4) = -3
U5 = a + 4b = -15 + 4(4) = 1
U6 = a + 5b = -15 + 5(4) = 5
U7 = a + 6b = -15 + 6(4) = 9
U8 = a + 7b = -15 + 7(4) = 13
U9 = a + 8b = -15 + 8(4) = 17
U10 = a + 9b = -15 + 9(4) = 21
10 suku pertama barisan trsbut adalah: -15, -11, -7, -1, 1, 5, 9, 13, 17, 21
Dik :
U1 = -15
U5 = 1
Dit :
a. b ?
b. U10 ?
c. 10 suku pertama ?
Jawab :
a. b(beda) = 1 + 15 / 5 – 1 = 4
b. U10 = U5 + 5b = 1 + 5(4) = 21
c.
U1 = -15 ,
U2 = -15 + 4 = -11
U3 = -15 + 2(4) = -7
U4 = -15 + 3(4) = – 3
U5 = -15 + 4(4) = 1
U6 = -15 + 5(4) = 5
U7 = -15 + 6(4) = 9
U8 = -15 + 7(4) = 13
U9 = -15 + 8(4) = 17
U10 = -15 + 9(4) = 21
SEMOGA MEMBANTU ^_^