Răspunsuri

2014-10-21T10:01:53+03:00
a) 5+10+15+20+......+1000=
=(1000+5)*[(1000-5):5+1]:2=
=1005*200:2=
=100500

b) 4+8+12+16+.......+400=
(400+4)*[(400-4):4+1]:2=
=404*100:2=
=20200


4 4 4