1^2+2^2+3^2+...2015^2
Những câu hỏi liên quan
Tinh:
S=2015 + 2015/1+2 +2015/1+2+3 + 2015/1+2+3+4 +... + 2015/1+2+3+...+2016
Tinh:
S=2015 + 2015/1+2 +2015/1+2+3 + 2015/1+2+3+4 +... + 2015/1+2+3+...+2016
2015 + (2015/ 1+2) + (2015/ 1+2+3) +......+ (2015/ 1+2+3+...+2014) =?
Lời giải:
$A=2015+\frac{2015}{1+2}+\frac{2015}{1+2+3}+...+\frac{2015}{1+2+3+...+2014}$
$=2015+\frac{2015}{\frac{2.3}{2}}+\frac{2015}{\frac{3.4}{2}}+....+\frac{2015}{\frac{2014.2015}{2}}$
$=2015+4030(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2014.2015})$
$=2015+4030(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2014}-\frac{1}{2015})$
$=2015+4030(\frac{1}{2}-\frac{1}{2015})=2015+2015-2$
$=4028$
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Tính S = 1/2(1+2) + 1/3(1+2+3)+...+ 1/2015(1+2+...+2014+2015) + 1/2016(1+2+...+2015+2016)
Tính tổng S= 2015 + 2015/1+2 + 2015/1+2+3 + ... + 2015/1+2+3+...+2016
viết lại đề cho rõ phân số đi bn
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Tính tổng S=2015+2015/1+2+2015/1+2+3+..........+2015/1+2+3+........+2016
tìm s
Tính S = 1/2(1+2) + 1/3(1+2+3)+...+ 1/2015(1+2+...+2014+2015) + 1/2016(1+2+...+2015+2016
Tính: (1*2015+2*2014+3*2013+...+2015*1)/(1*2+2*3+3*4+4*5+...+2015*2016)
Tính ;1+1/2×(1+2)+1/3×(1+2+3)+….+1/2015×(1+2+…+2015)
\(1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+...+\frac{1}{2015}\left(1+2+3+...+2015\right)\)
\(=1+\frac{1}{2}.2.3:2+\frac{1}{3}.3.4:2+...+\frac{1}{2015}.2015.2016:2\)
\(=1+\frac{3}{2}+\frac{4}{2}+...+\frac{2016}{2}=\frac{2+3+4+...+2016}{2}=\frac{2033135}{2}\)
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Rút gọn biểu thức:
M = \(\frac{3^9-2^3.3^7+2^{10}.3^2-2^{13}}{3^{10}-2^2.3^7+2^{10}.3^3-2^{12}}\)
N = \(\frac{1^{2015}+2^{2015}+3^{2015}+....+10^{2015}}{2^{2015}+4^{2015}+6^{2015}+....+20^{2015}}\)