S=0.2+2.4+4.6+.....+2n ( 2n+2 )
2/2.4+2/4.6+....+2/50.52
S =1/1.3-1/2.4+1/3.5-1/4.6+1/5.7 - 1/6.8+1/7.9-1/8.10
3.Tìm X:
2/2.4+2/4.6+....=2/x.(x+2)=4/9
Tính tổng sau:
1.3+2.4+3.5+4.6+.....+97.99+98.100
Tính tổng
4/2.4+4/4.6+4/6.8+.....+4/1008.2010
1/1.3 - 1/2.4 + 1/3.5 - 1/4.6+.....+1/97.99-1/98.100
\(tìmxbiết\dfrac{2}{2.4}+\dfrac{2}{4.6}+.....+\dfrac{2}{x.\left[x+2\right]}=\dfrac{4}{9}\)
