1+1/3+1/6+1/10+...+2/x(x+1)=3984/1993
Những câu hỏi liên quan
1+1/3+1/6+1/10+...+2/x.(x+1)=3984/1993
tìm x
\(1+\frac{1}{3}+\frac{1}{6}+...+\frac{2}{x\left(x+1\right)}=\frac{3984}{1993}\)
\(\Rightarrow\frac{2}{2}+\frac{2}{6}+\frac{2}{12}+...+\frac{2}{x\left(x+1\right)}=\frac{3984}{1993}\)
\(\Rightarrow\frac{2}{1.2}+\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{x\left(x+1\right)}=\frac{3984}{1993}\)
\(\Rightarrow2\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{x\left(x+1\right)}\right)=\frac{3984}{1993}\)
\(\Rightarrow2\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{3984}{1993}\)
\(\Rightarrow2\left(1-\frac{1}{x+1}\right)=\frac{3984}{1993}\)
\(\Rightarrow1-\frac{1}{x+1}=\frac{1992}{1993}\)
\(\Rightarrow\frac{1}{x+1}=\frac{1}{1993}\)
Mà x + 1 = 1993 <=> 1992
Vậy x = 1992
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Tìm x:
a: 1/45+1/55+1/66+.....+2/x*(x+1)=1/9
b:1+1/3+1/6+1/10+.....+1/x*(x+1):2=3984/1993
Tìm x biết 1+1/3+1/6+1/10+...+2/x(x+1)=1/1991/1993
Tìm x biết 1+1/3+1/6+1/10+...+2/x(x+1)=1/1991/1993
tìm x biết a, 1+1/3+1/6+1/10+.....+1/x.(x+1):2=1 1/1993
b,(x+8)+(x+9)+(x+10)+....+206+207=2007
18 tháng 1 2022 lúc 14:07
1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{6}\) + \(\dfrac{1}{10}\) +...+ \(\dfrac{1}{x\left(x+1\right):2}\) = \(1\dfrac{1991}{1993}\)
1+ 1/3+1/6+1/10+...+1/x.(x+1):2= 1 1991/1993
1 1991/1993 la hon so
Tìm x,biết rằng:
a)1/5.8+1/8.11+1/11.14+...1/x(x+3)=101/1540
b)1+1/3+1/6+1/10+...+1/x(x+1):2=1 1991/1993
*1 1991/1993 là hỗn số nha
14 tháng 3 2017 lúc 16:17
1+1/3+1/6+11/10+.......+1/x(x+1):2=1va 1991/1993