\(\frac{1}{2}+\frac{1}{6}+.....+\frac{1}{x\left(x+1\right)}=\frac{2015}{2016}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+......+\frac{1}{x\left(x+1\right)}=\frac{2015}{2016}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+......+\frac{1}{x}-\frac{1}{x+1}=\frac{2015}{2016}\)
\(=1-\frac{1}{x+1}=\frac{2015}{2016}\)
\(=\frac{1}{x+1}=\frac{1}{2016}\)
=> x + 1 = 2016
=> x =2015
1/2+1/6+1/12+1/20....+1/x(x+1)=2015/2016
1/2+1/6+1/12+1/20+...+1/x[x+1]=2015/2016
tim x
1/2+1/6+1/12+1/20+.......+1/x(x+1)=2015/2016
Tìm số tự nhiên x , biết rằng:
1/2+1/6+1/12+1/20+...+1/x(x+1)=2015/2016
1/2+1/6+1/12....+1/x(x+1)=2015/2016
Tìm số tự nhiên x, biết rằng:
\(1/2+1/6+1/12+1/20+...+1/x(x+1)=2015/2016\)
Tìm x:
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+.....+\)\(\frac{1}{x\left(x+1\right)}\)=\(\frac{2015}{2016}\)
tìm x biết 1/2+1/6+1/12+...+1/x.(x+1)=2015/2016
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