diketahui barisan aritmatika dengan U5=7 dan U8=13 suku ke 65 adalah

BARISAN ARITMATIKA
U5 = a+4b = 7
U8 = a+7b =13

U8–U5
(a+7b) – (a+4b) = 13–7
3b = 6
b = 6/3
b = 2

U5 = a+4b
7 = a+(4×2)
7 = a+8
a = 7–8
a = –1

U65 = a+44b
= –1 + (44×2)
= –1 + 88
= 87

U8 - U5 = U8 - ( 8-5 ) b + U8
6 = 3b
2 = b

U8 = U1 +(8-1) 2
13 = U1 + 14
13-14 = U1
-1 = U1

U65 = -1 +(65-1) 2
= -1 + 128
= 127


SEMOGA MEMBANTU !