作业帮数列求和,
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/06 03:59:54
x=o@ǿJT+8◻#vݝ8BbdP: !$&$XhN(qG]\F(pGOT g?V'Ϸ"q DpO {{{ձ{rY> fy-j(x /l{BPA qK@" 0A*HH)a0bL0%
Jaꡔ Jl'-~n$L J1B(E } #ƘlPUƝ(Q6^_? 2ImM5&#;ڲ LN,m,6o"?N6AQUUcglS0i%8\90']Lsµ NQ3m)kGX7Y]MQ> j5O>;bKbʺυT%/GکϿ~su\ws>t/f
数列求和,
数列求和,
数列求和,
Sn=[(1+3¹)/2¹]+[(1+3²)/2²]+[(1+3³)/2³]···+[(1+3ⁿ)/2ⁿ]
=(1/2¹+3¹/2¹)+(1/2²+3²/2²)+(1/2³+3³/2³)···+(1/2ⁿ+3ⁿ/2ⁿ)
=(1/2¹+1/2²+1/2³+···+1/2ⁿ)+(3¹/2¹+3²/2²+3³/2³+···+3ⁿ/2ⁿ)
=[(1/2¹)/(1-1/2)](1-1/2ⁿ)+[(3¹/2¹)/(1-3/2)](1-3ⁿ/2ⁿ)
=(1-1/2ⁿ)+(3ⁿ⁺¹/2ⁿ-3)
=3ⁿ⁺¹/2ⁿ-1/2ⁿ-2
和式=S
=lim(n↝+∞)Sn
=lim(n↝+∞)[3ⁿ⁺¹/2ⁿ-1/2ⁿ-2]
=+∞-0-2
=+∞
正无穷，求和式不收敛