admin百科知識 2022-02-12 17:28:01 設{an}爲等差數列則(1)d=-2,a16=1,求a2,s10 (2)d=13,n=37,sn=629求a1,an (3)a6=5,a3+a8=5,求s9設{an}爲等差數列則(1)d=-2,a16=1,求a2,s10 (2)d=1/3,n=37,sn=629求a1,an (3)a6=5,a3 a8=5,求s9(4)sn=5n² 3n,求a1,a2,a3及an網友廻答:匿名網友(1)a16=a1 15d a1=31a2=29S10=a1n n(n-1)d/2=220(2)S37=629=37a1 37*36*(1/3)/2 a1=11 an=11 1/3(n-1)=n/3 32/3(3)a3 a8=5=a6 a5a5=0S9=(a1 a9)9/2=2a5*9/2=0(4) a1=s1=8a2=18a3=28an=Sn-Sn-1=10n-2(n屬於N ) db標簽 生活常識_百科知識_各類知識大全»設{an}爲等差數列則(1)d=-2,a16=1,求a2,s10 (2)d=13,n=37,sn=629求a1,an (3)a6=5,a3+a8=5,求s9
0條評論