等差数列等比数列前n项和以及前n乘积的公式

an=a1q^(n-1)Sn = a1+a2+...+an = a1(q^n-1)/(q-1)Tn = a1.a2.a3...an = (a1)^n ( q.q^2...q^(n-1) )=(a1)^n . q^[n(n-1)/2]bn = b1+(n-1)d Sn =b1+b2+...+bn = (2b1+(n-1)d)n/2 Tn = b1.b2...bn = b1(b1+d)(b1+2d)...(b1...