6 dan 7 tolong dengan caranya

BARISAN BILANGAN

7. DERET ARITMATIKA
3 + 6 + 9 + ... + 45

beda = U2 - U1 = 6-3 = 3

Un = a + (n -1)b
45 = 3 + (n-1) 3
45 = 3 + 3n - 3
45 = 3n
45/3 = n
15 = n

Sn = n/2 ( a + Un )
S15 = 15/2 ( 3 + 45)
S15 = 7,5 (48)
S15 = 360 (d)



8. BARISAN GEOMETRI
4, 8, 16
ditanya = U10?

Rasio
= U2/U1
= 8/4
= 2

Un = a . r^(n-1)
U10 = 4 . 2^(10-1)
U10 = 4 . 2^9
U10 = 4 . 512
U10 = 2048


Semoga membantu :)

6. Un= U1+(n-1).b
U4= 3+3(3)
U4= 3+9
U4= 12
U5= 15
U6= 18
U7= 21
U8= 24
U9= 27
U10= 30
U11= 33
U12= 36
U13= 39
U14= 42
U15= 45
12+15+18+21+24+27+30+33+36+39+42+45=

7. Un= U1+(n-1).b+(n-1)(n-2).c:2
U10= 4+9(4)+9.8.4:2
U10=40+144
U10= 184

ga ada jawabannya maaf jika salah