2,
1/1×2 + 1/2×3 + 1/ 3×4 +…+1/2004×2005 + 1/2005×2006
1 tym + ctrlhn + 5*
2, 1/1×2 + 1/2×3 + 1/ 3×4 +…+1/2004×2005 + 1/2005×2006 1 tym + ctrlhn + 5*
By Lydia
By Lydia
2,
1/1×2 + 1/2×3 + 1/ 3×4 +…+1/2004×2005 + 1/2005×2006
1 tym + ctrlhn + 5*
1/1×2 + 1/2×3 + 1/ 3×4 +…+1/2004×2005 + 1/2005×2006
=1-$\frac{1}{2}$ + $\frac{1}{2}$ -$\frac{1}{3}$+$\frac{1}{3}$-$\frac{1}{4}$+$\frac{1}{4}$- $\frac{1}{5}$+…+$\frac{1}{2005}$-$\frac{1}{2006}$
=1-$\frac{1}{2006}$ =$\frac{2005}{2006}$
Đáp án:
Giải thích các bước giải:
`1/1.2+1/2.3+1/3.4+….+1/2004.2005+1/2005.2006`
`=1-1/2+1/2-1/3+1/3-1/4+….+1/2004-1/2005+1/2005-1/2006`
`=1-1/2006=2005/2006`