锟斤拷锟斤拷锟斤拷锟揭伙拷锟�(g锟斤拷)锟斤拷(sh锟斤拷)锟叫從第讹拷锟�(xi锟斤拷ng)锟斤拷锟斤拷每一锟�(xi锟斤拷ng)锟絚锟斤拷锟斤拷前一锟�(xi锟斤拷ng)锟侥诧拷锟斤拷锟酵�一锟斤拷(g锟斤拷)锟斤拷锟斤拷(sh锟斤拷)锟斤拷锟斤拷锟斤拷锟角等差數(sh锟斤拷)锟斤拷知锟絉(sh锟斤拷)锟絚(di锟斤拷n)锟斤拷锟結(ji锟斤拷)锟斤拷希锟斤拷锟斤拷(du锟斤拷)锟斤拷锟斤拷锟叫庯拷锟斤拷锟斤拷

锟斤拷锟斤拷1.锟斤拷锟絰锟斤拷锟斤拷锟揭伙拷锟�(g锟斤拷)锟斤拷(sh锟斤拷)锟斤拷,锟侥第讹拷锟�(xi锟斤拷ng)锟絖始锟斤拷锟斤拷每一锟�(xi锟斤拷ng)锟絚前一锟�(xi锟斤拷ng)之锟筋都锟斤拷锟斤拷同一锟斤拷锟斤拷(sh锟斤拷)锟斤拷锟紷锟斤拷(g锟斤拷)锟斤拷(sh锟斤拷)锟叫就叫等差數(sh锟斤拷)锟斤拷,锟紷锟斤拷(g锟斤拷)锟斤拷锟斤拷(sh锟斤拷)锟斤拷锟斤拷锟饺差數(sh锟斤拷)锟叫的癸拷锟斤拷锟斤拷通锟斤拷锟斤拷锟斤拷母d锟斤拷(l锟斤拷i)锟斤拷示锟斤拷同锟接為數(sh锟斤拷)锟叫的等比旓拷(sh锟斤拷)锟叫碉拷锟斤拷锟絴(zh锟斤拷)锟絚锟饺差數(sh锟斤拷)锟斤拷也锟斤拷锟斤拷通之處锟斤拷

锟斤拷锟斤拷2.锟斤拷(sh锟斤拷)锟叫烇拷炔顢�(sh锟斤拷)锟叫的筹拷要锟絣锟斤拷锟角ｏ拷锟斤拷(sh锟斤拷)锟叫碉拷前n锟�(xi锟斤拷ng)锟斤拷S锟斤拷锟皆岋拷锟斤拷S=an^2+bn锟斤拷锟斤拷式(锟斤拷锟斤拷a锟斤拷b锟介常锟斤拷(sh锟斤拷)).锟饺差數(sh锟斤拷)锟叫撅拷锟斤拷(x锟斤拷)锟絵

锟斤拷锟斤拷3.锟斤拷锟絴(zh锟斤拷)1锟斤拷锟斤拷锟斤拷锟絛锟侥等差數(sh锟斤拷)锟叫ｏ拷锟斤拷锟�(xi锟斤拷ng)同锟斤拷锟皆筹拷锟斤拷(sh锟斤拷)k锟斤拷锟矫旓拷(sh锟斤拷)锟斤拷锟斤拷锟角等差數(sh锟斤拷)锟斤拷锟斤拷锟戒公锟斤拷锟絢d.

锟斤拷锟斤拷4.锟斤拷锟絴(zh锟斤拷)2锟斤拷锟斤拷锟斤拷锟絛锟侥等差數(sh锟斤拷)锟叫ｏ拷锟斤拷锟�(xi锟斤拷ng)同锟斤拷一锟斤拷(sh锟斤拷)锟斤拷锟矫旓拷(sh锟斤拷)锟斤拷锟斤拷锟角等差數(sh锟斤拷)锟斤拷锟斤拷锟戒公锟斤拷锟皆烇拷d.

锟斤拷锟斤拷5.锟斤拷锟絴(zh锟斤拷)3锟斤拷锟斤拷(d锟斤拷ng)锟斤拷锟斤拷d>0锟絩(sh锟斤拷)锟斤拷锟饺差數(sh锟斤拷)锟斤拷锟叫的旓拷(sh锟斤拷)锟絊锟�(xi锟斤拷ng)锟斤拷(sh锟斤拷)锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟�;锟斤拷(d锟斤拷ng)d<0锟絩(sh锟斤拷)锟斤拷锟饺差數(sh锟斤拷)锟斤拷锟叫的旓拷(sh锟斤拷)锟絊锟�(xi锟斤拷ng)锟斤拷(sh锟斤拷)锟侥減锟劫讹拷锟絧小;d=0锟絩(sh锟斤拷)锟斤拷锟饺差數(sh锟斤拷)锟斤拷锟叫的旓拷(sh锟斤拷)锟斤拷锟斤拷一锟斤拷(g锟斤拷)锟斤拷锟斤拷(sh锟斤拷).

锟斤拷锟絇(gu锟斤拷n)锟斤拷锟絔锟斤拷

锟斤拷锟斤拷锟竭匡拷锟斤拷(sh锟斤拷)锟絎(xu锟斤拷)知锟絉(sh锟斤拷)锟絚(di锟斤拷n)锟絉锟斤拷

锟斤拷锟铰高匡拷锟結訊锟斤拷锟竭匡拷锟斤拷锟斤拷锟斤拷锟斤拷前锟斤拷(zh锟斤拷n)锟戒、志愿锟斤拷锟�(b锟斤拷o)锟斤拷锟饺★拷锟�?j锟斤拷n)?sh锟斤拷)锟斤拷锟斤拷

锟竭匡拷锟絩(sh锟斤拷)锟絞锟斤拷锟斤拷全锟斤拷锟斤拷要锟斤拷(ji锟斤拷)锟絚(di锟斤拷n)

锟組锟斤拷"锟竭匡拷锟絎(w锟斤拷ng)"微锟脚癸拷锟斤拷號(h锟斤拷o)