tinh tong :S=1-2+3-4+5-6+...+2015-2016
Tinh tong S=1/1×2+1/2×3+1/3×4+...+1/2014×2015+1/2015×2016
\(S=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+....+\frac{1}{2015.2016}\)
\(S=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{2015}-\frac{1}{2016}\)
\(S=1-\frac{1}{2016}=\frac{2015}{2016}\)
\(S=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-........+\frac{1}{2015}-\frac{1}{2016}\)
\(S=\frac{1}{1}-\left(-\frac{1}{2}+\frac{1}{2}\right)+\left(-\frac{1}{3}+\frac{1}{3}\right)+......+\left(-\frac{1}{2015}+\frac{1}{2015}\right)-\frac{1}{2016}\)
\(S=\frac{1}{1}-\frac{1}{2016}=\frac{2015}{2016}\)
Tinh tong S=1/1×2+1/2×3+1/3×4+...+1/2014×2015+1/2015×2016
S = 1/1x2 + 1/2x3 + 1/3x4 + ... + 1/2014x2015 + 1/2015x2016
S = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/2014 - 1/2015 + 1/2015 - 1/2016
S = 1 - 1/2016
S = 2015
\(S=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-......+\frac{1}{2015}-\frac{1}{2016}\)
\(S=\frac{1}{1}-\frac{1}{2016}=\frac{2015}{2016}\)
tinh tong
(-40)+(-39)+....+33+34+35
b) 1+2-3-4+5+6-7-8+9+...+2013+2014-2015-2016
tinh hanh cac tong sau
a.A=2+4+6+.....+2018
B=2010-2017+2016-2015+......+2-1
tinh tong S = 1-2+3-4+...+2016-2016
Vậy mình nói thảng nhé. Đề này sai số rồi.
Đề đúng như thế này mới hợp lí chứ:
S = 1-2+3-4+...+2015-2016
S= (1-2)+ (3-4) +...+ (2015-2016)
S= (-1)+ (-1)+...+ (-1)
S có 2016 số hạng => Có 1008 số (-1)
=> S= 1008. (-1) =-1008
Vậy S= -1008
tinh tong
S = 1 + 3 + 5 + ...+ 99
A = 1 + 2 + 3 + ...+100
B = 2 + 4 + 6 + ..+ 2016
*chu y : neu quy luat
Tim chu so tan cung cua tong
1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 + 5 x 6 + ...... + 2015 x 2016
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