<prompt> Msururu usio na kikomo wa nambari halisi a_1, a_2, dots inatosheleza kujirudia a_n3 a_n2 - 2a_n1 a_n kwa kila nambari kamili n. Kwa kuzingatia kwamba a_1 a_3 1 na a_98 a_99, hesabu a_1 a_2 dots a_100.  <response>: Kuandika kujirudia kwa n 1, 2, 3, dots, 97, tunayoanzailiyopangwaa_4 a_3 - 2a_2 a_1 a_5 a_4 - 2a_3 a_2 a_6 a_5 - 2a_4 a_3 ;,vdots a_100 a_99 - 2a_98 a_97.mwishozilizowianishwaKwa muhtasari wa 97 wa milinganyo hii, tuna a_4 vitone a_100 a_3 vitone a_99 - 2a_2 vitone a_ 98 a_1 vitone a_97.Hebu S a_1 a_2 vitone a_100. Kisha tunaweza kuandika upya mlingano ulio hapo juu kulingana na S kama S - a_1a_2a_3 S - a_1a_2a_100 - 2S - a_1a_99a_100 S-a_ 98a_99a_100,au S - a_1 - a_2 - a_3 a_1 - a_2 - a_98 a_99.Hivyo, S 2a_1 a_3 - a_98 a_99.Kwa kuwa a_1 a_3 1 na a_98 a_99, tunapata S 21 1 3. 