Dari suatu deret diketahui 
= 
- 15n. Nilai 
= 0 untuk n = ....
A. 1
B. 2
C. 3
D. 4
E. 5
A. 1
B. 2
C. 3
D. 4
E. 5
IcukSugiarto
![\bold{\underline{Smart\ Solution\ Version\ 1:}}\\U_{n}=S_{1}+(n-1)2p\\U_{n}=3-15+(n-1)2(3)\\U_{n}=-12+(n-1)6\\U_{n}=-12+6n-6\\U_{n}=6n-18\\ingat\ nilai\ U_{n}=0, maka:\\0=6n-18\\6n=18\\~~n= \frac{18}{6}\\~~n=3~~~~~~~~~\bold{[Solved\ C.3]}](https://tex.z-dn.net/?f=%5Cbold%7B%5Cunderline%7BSmart%5C+Solution%5C+Version%5C+1%3A%7D%7D%5C%5CU_%7Bn%7D%3DS_%7B1%7D%2B%28n-1%292p%5C%5CU_%7Bn%7D%3D3-15%2B%28n-1%292%283%29%5C%5CU_%7Bn%7D%3D-12%2B%28n-1%296%5C%5CU_%7Bn%7D%3D-12%2B6n-6%5C%5CU_%7Bn%7D%3D6n-18%5C%5Cingat%5C+nilai%5C+U_%7Bn%7D%3D0%2C+maka%3A%5C%5C0%3D6n-18%5C%5C6n%3D18%5C%5C%7E%7En%3D+%5Cfrac%7B18%7D%7B6%7D%5C%5C%7E%7En%3D3%7E%7E%7E%7E%7E%7E%7E%7E%7E%5Cbold%7B%5BSolved%5C+C.3%5D%7D+ "\bold{\underline{Smart\ Solution\ Version\ 1:}}\\U_{n}=S_{1}+(n-1)2p\\U_{n}=3-15+(n-1)2(3)\\U_{n}=-12+(n-1)6\\U_{n}=-12+6n-6\\U_{n}=6n-18\\ingat\ nilai\ U_{n}=0, maka:\\0=6n-18\\6n=18\\~~n= \frac{18}{6}\\~~n=3~~~~~~~~~\bold{[Solved\ C.3]}")
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