Question

Tolong di bantu yh kk buat besok :)

Answer 1

16) U6/U3 = 192/24
=> ar^5/ar^2 = 8
=> r^3 = 2^3
=> r = 2
U3 = ar^2
24 = a(2)^2
a = 24/4 = 6
S7 = a(r^7 - 1)/(r - 1) = 6(2^7 - 1)/(2 - 1) = 6(128 - 1)/1 = 6(127) = 762
Tak ada di option

Mungkin yang ditanya suku ke 7
U7 = ar^6 = 6(2)^6 = 6(64) = 384

17) 105, 110, 115, .... , 195
Un = a + (n - 1)b
195 = 105 + (n - 1)5
195 = 105 + 5n - 5
195 = 100 + 5n
95 = 5n
n = 95/5 = 19
Sn = n/2 (a + Un)
S19 = 19/2 (105 + 195) = 19/2 (300) = 19(150) = 2.850
Tak ada di option jg

18) 202, 204, 206, .... , 298
Un = a + (n - 1)b
298 = 202 + (n - 1)2
298 = 202 + 2n - 2
298 = 200 + 2n
98 = 2n
n = 98/2 = 49
Sn = n/2 (a + Un)
S49 = 49/2 (202 + 298) = 49/2 (500) = 49 (250) = 12.250