求解谢谢_百度知道
某市大力发展新能源汽车。2014年4月为了减少汽车尾气排放，改善城市空气质量，从2013年5月起，该市投放到市场300辆新能源汽车；从2013年4月起，计划每月比上一月都投放75辆。求2015年3月，该市计划投放多少辆新能源汽车，需要多少个月(包括2014年4月)
提问者采纳
：需要25个月;2=30000(x-25)(x+32)=0∵x&gt：设需要x个月(包括2014年4月)：+（300+75）+（300+2x75）+···+[300+（x-1）75]设300+（300+75）+（300+2x75）+···+[300+（x-1）75]为数列AnSn=xa1+x(x-1)d/2=300x+75x(x-1)/0∴x=25答，该市计划投放新能源汽车的总量达到30000辆由题
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出门在外也不愁左主客至，右主官非 是什么意思 求解谢谢了
左主客至，右主官非 是什么意思 求解谢谢了 5
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主人的客 或者说家里重要成员 远亲 要来访
主官非 不懂
主官非 我理解为 出门慎重言\行
右主官非一
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