Question

Tolong dijawab yah kak nomor 7 8 9 10 plus kak besok dikumpul

Answer 1

9. Sn < 0 = a(1-r^n)/1-r
S5 = a(1-r^5)/1-5
-93 = a(1-32)/-4
-93 * -4 = -31a
372 = -31a
a = -12

U1 = a = -12
U3 = ar^2 = -12.4 = -48

10.
U1 = a = 8
r = 3
Un = 5832

* 5832 = a3^n-1
5832 = 8.3^n-1
5832/8 = 3^n-1
729 = 3^n
n-1 = ∛729
n-1 = 9
n = 10

S10
= a(r^10 - 1)/r-1
= 8(59049-1)/9
= 52287,1