Sn=3*3+5*3^2+7*3^3+...+(2n+1)3^n怎么用错位相减求Sn?
Sn=1*5+3*5^2+5*5^3+.+(2n-1)*5^n 求Sn (错位相减) 求完整步骤,
错位相减法数列求和Sn=x+3x+5x^2+7x^3+…+(2n-1)*x^(n-1)(x≠0)
错位相减法的题如:求和Sn=1+3x+5x^2+7x^3+…+(2n-1)*x^(n-1)(x≠0)当x=1时,Sn=1
Sn=3+2^n Sn-1=3+2^(n-1).则Sn-Sn-1=?
用错位相减法求和,Sn=2*1/3+3*1/3²+4*1/3³...+(n-1)*1/3^n
错位相减法求和:求和:Sn=1+3x+5x2+7x3+…+(2n-1)xn-1.
数列an的前n项和Sn满足Sn=3n+1,n≤5,Sn=n^2,n≥6,求通项公式
Sn=1x2+3x2^2+5x2^3+…+(2n-1)x2^n sn=2sn-sn
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
设Sn=-1+3-5+7-…+(-1)n(2n-1),则Sn=______.
(1).Sn=1+2×3+3×7...n(2^n-1),求Sn.
数列Sn=(3n+1)/2-(n/2)an