68音{pinyin：yīn}频

124.68 324.68 524.68 724.68 924.68怎样计算？上式各项成等差数列首项为124.68，公差为200根据等差数列求和公式则有124.68 324.68 524.68 724

124.68 324.68 524.68 724.68 924.68怎样计算？

上式各项成等差数列首项为124.68，公差为200根据等差数列求和公式则有124.68 324.68 524.68 724.68 924.68=#28124.68 924.68#29#2A5/2=524.68#2A2#2A5/2=5246.8/2=2623.4

124.68 324.68 524.68 724.28 924.68

=100 300 500 700 900 24.68#2A5

=2500 123.4

上式各项成等差数列

首{shǒu}项为124.68，公差为200

根{piny澳门新葡京in：gēn}据等差数列求和公式则有

124.68 324.68 524.68 724.68 924.68

=2623.4