`2/(3xx5)+2/(5xx7)+...+2/(13xx15)+2/(1xx2)+2/(2xx3)+...+2/(9xx10)`
`=1/3-1/5+1/5-1/7+...+1/13-1/15+2(1/(1xx2)+1/(2xx3)+...+1/(9xx10))`
`=1/3-1/15+2(1-1/2+1/2-1/3+...+1/9-1/10)`
`=4/15+2(1-1/10)`
`=4/15+2*9/10`
`=4/15+9/5`
`=4/15+27/15`
`=31/15`
giup tui nha . dau nhan tui viet la dau (.) nay nha
8.9.14+6.7.12+19.4.18
giai giup minh bai 5 voi 
cac bn giai giup mik vs
co ai choi bang bang ko tui giup cho
4x-15=-75-x
Giup tui nha
so sanh 2 100 va 1024 8
giup minh vo giai va giai chi tiet
mn giup mik giai bai nay voi
mn giup minh nhe
cam on cac ban da giup giai bai toan nay
giup mik giai phep tinh nay 2x+3x=5
chieu mik di hoc roi giup mik nha
