admin百科知識 2022-02-13 18:00:56 在等差數列｛an｝中,若a1＋a4＋a6＋a8＋a10＋a12=120,則a9＋13a11的值爲?在等差數列｛an｝中,若a1＋a4＋a6＋a8＋a10＋a12=120,則a9＋1/3a11的值爲?網友廻答：匿名網友a1＋a4＋a6＋a8＋a10＋a12=120a1 a1 3d a1 5d a1 7d a1 9d a1 11d=1205(a1 7d)=1205a8=120a8=24a9-1/3a11=a1 8d-1/3(a1 10d)=2/3 a1 14/3 d=2/3(a1 7d)=2/3a8=16 db標簽 生活常識_百科知識_各類知識大全»在等差數列｛an｝中,若a1＋a4＋a6＋a8＋a10＋a12=120,則a9＋13a11的值爲?
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