Tìm x biết:
1+1/3+1/6+1/10+...+1/x.x+1 :2=1/1993/1991
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
Tìm số tự nhiên x, biết : 1+1/3+1/6+1/10+.......+1/x.(x+1):2 = 1+1991/1993
Tìm x biết 1 + 1/3 + 1/6 + 1/10+ ................+ 1/ x ( x +1 ) :2 = 1 + 1991/1993
Dấu '' / '' thay cho dấu gạch ngang của phân số.
1 + 1/3 + 1/6 + 1/10 + .......... + 1/x.(x+1):2 =1 + 1991/1993
1/2.(1 + 1/3 + 1/6 + 1/10+........+ 1/x.(x+1):2=3984/3986
1/2 + 1/6 +1/12 + .......... +1/x.(x+1)=3984/3986
1/1.2 + 1/2.3 + 1/3.4 +..........+.1/x.(x+1)=3984/3986
2-1/1.2 + 3-2/2.3 + 4-3/3.4 +..........+ x + 1 - x/x.(x+1)
1-1/2+1/2-1/3+1/3-1/4+..........+1/x -1/x+1 =3984/3986
1-1/x+1=3984/3986
1/x+1=1-3984/3986
1/x+1=2/3986=1/1993
x+1=1993
x =1993-1
x =1992
cảm ơn nhé thế là bai về nhà mình đã giải quyết xong
tìm x biết
1/5.8+1/8.11+1/11.14+...+1/x(x+3)=101/15401+1/3+1/6+1/10+...+1/x(x+1):2=1 1991/1993Tìm x, biết rằng:
\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+1\right):2}=1\frac{1991}{1993}\)
Tìm x biết:
\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+3\right):2}=1\frac{1991}{1993}\)
Tìm x biết
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
a)\(\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{3}\left(\frac{3}{5\cdot8}+\frac{3}{8\cdot11}+...+\frac{3}{x\left(x+3\right)}\right)=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{3}\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right)=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{308}\)
\(\Leftrightarrow x+3=308\Leftrightarrow x=305\)
b ko hiểu đề
tìm x biết
\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+1\right):2}=1\frac{1991}{1993}\)
1+ 1/3+1/6+1/10+...+1/x.(x+1):2= 1 1991/1993
1 1991/1993 la hon so