nomor 17 tolong di jawab pake cara kerjanya. pleaseeee

S5 = -33
r = -2

Ditanya U3 dan U4

Jawaban :
==========

[tex]s5 = \frac{a(1 - {r}^{5}) }{1 - r} \\ - 33 = \frac{a(1 - ( { - 2}^{5}) }{1 + 2} \\ - 33 = \frac{a(1 + 32)}{3} \\ - 99 = 33a \\ - \frac{99}{33} = a \\ - 3 = a[/tex]

Maka,
➡Suku ke 3

U3 = a x r^(3-1)

U3 = (-3) x (-2)²

U3 = -3 x 4

U3 = -12

➡Suku ke 4

U4 = a x r^(4-1)

U4 = (-3) x (-2)³

U4 = -3 x (-8)

U4 = 24


Sehingga :

=U3 + U4
= -12 + 24
= 12

17)
D5 = -33
r = -2

Dn = [a(1 - r^n)]/[1 - r]
D5 = [a(1 - r^5)]/[1 - r]
-33 = [a(1 - (-2)^5]/[1 - (-2)]
-33 = [a(1 - (-32)]/[1 + 2]
-33 = [a(1 + 32)]/3
-33 × 3 = a(33)
-99 = 33a
a = -99/33
a = -3

Sn = ar^(n-1)
S3 = -3(-2)^(3-1)
S3 = -3(-2)^2
S3 = -3(4)
S3 = -12

Sn = ar^(n-1)
S4 = -3(-2)^(4-1)
S4 = -3(-2)^3
S4 = -3(-8)
S4 = 24

S3 + S4
= -12 + 24
= 12