So sánh: a = 2/60.63 + 2/63.65 + ... + 2/117.120 + 2/2003 và b = 5/40.44 + 5/44.48 + ... + 5/76.80 + 5/2003

a= 2/60.63 + 2/63.65 +....+ 2/117.120 +2/2003 va b=5/40.44 + 5/44.48 +...+ 5/76.80 +5/2003
2 c=2017/1.2+2017/3.4+......+2017/99.100 va d=2018.51+2018.52+.............+2018/100