? ?: ??????????????????,????????,????????????????????????????????,?????????????????????????????????????????
???: ???? ???? ??????
??????????????????????????,????????????,???????????,???????????????????????????n??????????,??????????????????,??????????????????????????????????????????
???????????
??????????????,????????????????,????????????????????
?1:?????(????)??????????????????????11???????,?????,11?1?,????????????20?,??,????????????????????50??????????????,????????????,????,????????????????????30?,?11?30??,????30????????????8670?,?11???,????????????????????????????
??:?11?n??????????,???????11?1??n?,???????????????;?n+1??30?,?????????????????????????????????????
??:???,11?1??n?,???????????????a,a=20,d=50,11?n???????a=50n-30;?n+1??30?,??????????????b,b=50n-60,d=-30,b=(50n-60)+(n-1)(-30)=20n-30,11?30????????b=20(30-n)-30=-20n+570?
????????:+=8670,???:n-61n+588=0,??n=12?n=49(?),?11?12???????????,?570??
????a-a=f(n),f(n)????????????????
?????????????,a?a??(??)??????,??????f(n)?????????????,????????????????
?2:???????????,???????,???????,????????????a?????,???b????????,????n????????(n-1)???????(n?N)?
(1)??????s?n??????;
(2)?a=10,b=4000????????????????????,???????
??:??(1)??????,?????n???????s,?s??????(n-1)?????,???,s-s=,????{s}???????????,????????????,??????????????????
???:????:??,s=b++++.+=b(2-)?
(????1???,s=b+;2???,s=b++;.;n???,s=b++++.+?)
???:(?????)?s??????0???????,
??:s-s=s-s=..s-s=,???S-S=+++.+,
?s=b++++.+=b(2-)?
(2)?b=4000?,s=4000(2-),????t,??t=s#8226;10-1000n=40000(2-)-1000n?
??T??,?:T?TT?T,?n?5n?5,?n=5,??s=7875?
???????7875???,?5?????,???????
??a=C#8226;a+B,??B?C??????C?1????????
?3:?????1???????????,?????25%,?????????,?????????????200????????????????,????????????,???????,????????????????(4?)????(lg2=0.3)?
??:???n??,???????a??,?????????a?a???????:a=a(1+25%)-200(n?2),???????????,?????"?????"?
?:??,a=a(1+25%)-200(n?2),?a=a-200,?a+?=(a+?),???a=a+?,?=-200,?=-800??a-800=(a-800),?{a-800}???????,a=1000(1+25%)-200=1050,a-800=250,?a-800=250(),a=250()+800,?a?4000,?()?16,??n?12,?????12????????
????(???)???????????
?????????????????????????,??????,??????????????,?????
?4:?????????????10%?20%?????500ml,????????????100ml??,???????????,????????,?a=10%,b=20%,?(n-1)?????????????????a?b,
(1)??a?b??a?b;
(2)????{a-b}?????,???a?b????
??:????????????a?b,??????????????,??????????????,???????????????
?:(1)???:
a==a+b;b==b+a?
(2)a-b=a-b=(a-b)(n?2),
?{a-b}???????a-b=-10%,
?a-b=-10%()(1)
??a+b=a+b=.=a+b=30%(2)
??(1)?(2)?a=-()#8226;5%+15%;b=()#8226;5%+15%?
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