Dik deret aritmetika dengan Sn = 5n - nkuadrat
tentukan U100 + U101 + .... + U120
tolong pake cara dan penjelasan ya
tentukan U100 + U101 + .... + U120
tolong pake cara dan penjelasan ya
Takamori37
Maka,
![$\begin{align}U_{100}+\dots+U_{120}&=S_{120}-S_{99} \\ &=[5(120)-120^2]-[5(99)-99^2] \\ &=(600-14400)-(495-9801) \\ &=-13800-(-9306) \\ &=-4494\end{align}](https://tex.z-dn.net/?f=%24%5Cbegin%7Balign%7DU_%7B100%7D%2B%5Cdots%2BU_%7B120%7D%26%3DS_%7B120%7D-S_%7B99%7D+%5C%5C+%26%3D%5B5%28120%29-120%5E2%5D-%5B5%2899%29-99%5E2%5D+%5C%5C+%26%3D%28600-14400%29-%28495-9801%29+%5C%5C+%26%3D-13800-%28-9306%29+%5C%5C+%26%3D-4494%5Cend%7Balign%7D "$\begin{align}U_{100}+\dots+U_{120}&=S_{120}-S_{99} \\ &=[5(120)-120^2]-[5(99)-99^2] \\ &=(600-14400)-(495-9801) \\ &=-13800-(-9306) \\ &=-4494\end{align}")
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