题目

在无土栽培中用每升溶液含有0.5 molNH4Cl、0.16 molKCl、0.24molK2SO4溶质的溶液作为营养液，若用KCl、NH4Cl和(NH4)2SO4三种物质来配制1.00L上述营养液，所需三种盐的物质的量是A.0.4mol、0.5mol、0.12mol             B.0.66mol、0.5mol、0.24molC.0.64mol、0.5mol、0.24mol            D.0.64mol、0.02mol、0.24mol  答案：D解析:略  已知数列{an}满足：＝n2＋n(nN*)求： (Ⅰ)数列{an}的通项公式； (Ⅱ)数列{an}前n项和Sn．