No 6-8 harap bantuannyaaa

6) U5 = 500
a + 4 b = 500
U12 = 850
a + 11 b = 850
( a + 4b ) + 7b = 850
( 500 ) + 7b = 850
' 7b = 850 - 500
7b = 350
' b = 350/7 = 50
a + 4b = 500
a +4.50 = 500
a + 200 = 500
a = 500 - 200 = 300
7) a = 100, r = 2, n = 3 jam /15 menit = 12
Sn = a ( r^n - 1 ) / ( r 1 )
S12 = 100 ( 2^12 - 1 ) / ( 2-1 )
= 100 ( 4.096 - 1 ) / 1
= 100 ( 4.095 )
= 409.500
8) a = 5, U6 = ar^5 = 1.215
5.r^5 = 1.215
r^5 = 243
r^5 = 3^5
r = 3
Sn = a ( r^n - 1 ) / ( r - 1 )
S6 = 5 ( 3^6 - 1 ) / ( 3 - 1 )
= 5 ( 729 - 1 ) / 2
= 5 x 364
= 1.820 cm



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6.
U₅ = 500
U₁₂ = 850

Rumus cepat mencari beda
[tex] b = \frac{U_{12}-U_{5}}{12-5} [/tex]
[tex] b = \frac{850-500}{7} [/tex]
[tex] b = \frac{350}{7} [/tex]
b = 50

[tex] U_5 = a + 4b [/tex]
500 = a + 4(50)
a = 500 - 200
a = 300
Jadi produksi telur hari pertama = 300 butir

7.
n = 3 jam = 3 x 60 = 180 menit
p = 180 : 15 = 12 kali
a = 100
r = 2

[tex] U_p = ar^p[/tex]
=>100 • 2¹²
=>100 • 4096
=>409600

8.
[tex] U_1 = 5 , U_6 = 1215 [/tex]
Rumus cepat rasio

[tex] r = (\frac{U_6}{U_1})^{\frac{1}{6-1}}
[/tex]
[tex]r = (\frac{1215}{5})^{\frac{1}{5}} [/tex]
[tex] r = \sqrt[5]{243} [/tex]
r = 3

Maka
[tex] Sn = \frac{a(r^n-1)}{r-1} [/tex]
[tex] S_6 = \frac{5(3^6-1)}{(3-1)} [/tex]
[tex] S_6 = \frac{5(728)}{2} [/tex]
[tex] S_6 = 5 \times 364 [/tex]
=>1820 cm