= 1/1.2 + 1/2.3 + 1/3.4 + 1/4.5 + 1/5.6
= 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
= 1-1/6 = 5/6
k mk nha
1/2+1/6+1/12+1/20+1/30=5/6
MK ĐANG ÂM NÈ K ĐI LÀM ƠN
1/2+1/6+1/12+1/20+1/30
=1/1×2+1/2×3+1/3×4+1/4×5+1/5×6
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=1-1/6
=5/6
T i c k cho mình nhé!
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)
=\(\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{5}-\frac{1}{6}\)
=\(1-\frac{1}{6}\)=\(\frac{5}{6}\)