Materi : Barisan dan Geometri
U3 = 17 = a(r²)
U5 = 405 = a(r⁴)
U9 = ... = a(r⁸)
Rasio
(r⁴/r²) = 405/17
r² = 405/17
r = √( 405/17 ) = z
Suku Pertama
a = 17/√(405/17)
a = 17√(405/17) ÷ 405/17
a = 17[ 405/17 ]¹/²-¹
a = 17√( 405/17 )-¹
a = 17√( 17/405 ) = 17z-¹
Langsung Saja
Pemisalan √( 405/17 ) = z = r
\_____________________/
U9 = ( 17z-¹ )( z⁹-¹ )
U9 = ( 17z-¹ )( z⁸ )
U9 = 17z⁷
U9 = 17( 405/17 )³√(405/17)
U9 = 405³/17²√(405/17)
U9 = 1.121.941,668... ( 3.s.f )
U9 ~ 1.121.941,7
U9 ~ 1.121.942
Semoga bisa membantu
[tex] \boxed{ \colorbox{navy}{ \sf{ \color{lightblue}{ Answer\:by\: BLUEBRAXGEOMETRY}}}} [/tex]
Penjelasan dengan langkah-langkah:
diketahui
suku ke-3=17 dan suku ke-5=405
ditanya
suku ke 9
jawab
rasio
√(U5/U3)
√(405/17) = x
maka U1
a = 17/√(405/17)
a = 17(405/17 ])¹/²-¹
a = 17√( 405/17 )-¹
a = 17√( 17/405 )
a = 17x-¹
U9 = ( 17x-¹ )( x⁹-¹ )
U9 = 17x⁷
U9 = 17( 405/17 )³√(405/17)
U9 = 1.121.941,..
U9 = 1.121.941,7
U9 = 1.121.942
[answer.2.content]
