“微信扫一扫”进入题库练习及模拟考试

高中数学选择性必修 第二册(381题)



已知函数  \(f(x) = \frac{1}{3}{x^3} + 4x\)  ,记等差数列  \(\left\{ {{a_n}} \right\}\)  的前\(n\)项和为 \({S_n}\) ,若\(f\left( {{a_1} + 2} \right) = 100\) , \(f\left( {{a_{2022}} + 2} \right) = - 100\) ,则 \({S_{2022}} = \)( )



A.\( - 4044\)

B.\( - 2022\)

C.2022

D.4044


知识点:第四章 数列


参考答案:A


解析:

解:因为 \(f( - x) = - \frac{1}{3}{x^3} - 4x = - f(x),\therefore f(x)\) 是奇函数,

因为 \(f\left( {{a_1} + 2} \right) = 100\)\(f\left( {{a_{2022}} + 2} \right) = - 100\),所以 \(f\left( {{a_1} + 2} \right) = - f({a_{2022}} + 2)\)

所以 \({a_1} + 2 + {a_{2022}} + 2 = 0\),所以 \({a_1} + {a_{2022}} = - 4\)

所以 \({S_{2022}} = \frac{{2022}}{2}({a_1} + {a_{2022}}) = - 4044\). 故选:A

进入考试题库