kak bantuin lagi y..makasih

jawab

6.
2,5,8,11,14

a= 2,

b = 5-2
b= 3

u42 = a + 41b
= 2 + 42(3)
= 2 + 126
= 128

7.
1,2,4,8,...
a = 1
r = 2
un = a rⁿ⁻¹
un = 2ⁿ⁻¹ 

8.
u5 = 18
u11= 42
u11 - u5 = 42 - 18
(11-5) b = 24
6b = 24
b  = 4

u5  =18
a+ 4b = 18
a = 18 - 4b = 18 - 4(4)
a = 18 -16
a = 2
sn = n/2  (2a + (n-1)b)
s30 = 30/2 (2(2) + 29(4))
s30 = 15 ( 4 + 116)
s30 = 15(120) =
s30= 1.800

9.
u8 = 22
u12= 34

u12  - u8 =  34 -22
4b = 12
b = 3

a= 22 - 7b
a = 22 -21
a = 1


Sn = n/2 { 2a + (n-1)b}
s24 = 24/2 ({ 2(1) + 23(3)}
s24 = 12 (2 + 69)
s24 =  852