ta biết
1/1.2=1/1-1/2;1/2.3=1/2-1/3............;1/n-1/n+1=1/n(n+1)
=>1/1.2+1/2.3+............+1/100.101
=1/1-1/2+1/2-1/3+1/3-1/4+..............+1/99-1/100+1/100-1/101
=1-1/101=100/101
ta biet
1/1.2=1/1-1/2;1/2.3=1/2-1/3............;1/n-1/n+1=1/n(n+1)
=>1/1.2+1/2.3+............+1/100.101
=1/1-1/2+1/2-1/3+1/3-1/4+..............+1/99-1/100+1/100-1/101
=1-1/101=100/101
k mk nha
ta biết
1/1.2=1/1-1/2;1/2.3=1/2-1/3............;1/n-1/n+1=1/n(n+1)
=>1/1.2+1/2.3+............+1/100.101
=1/1-1/2+1/2-1/3+1/3-1/4+..............+1/99-1/100+1/100-1/101
=1-1/101=100/101