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simolifica fractiile:1+2+3+.... +29 pe2+4+6+. . .+40;2+4+6+....200 pe3+6+9+....300

Răspuns :

1+2+3+....+29= (29*30)/2 =29*15=435

2+4+6+....+40
2(1+2+3+..+20)
1+2+3+...+20 = (20*21)/2=10*21=210
210*2=420

3+6+9+...+300
3(1+2+3+...+100)
1+2+3+...+100=(100*101)/2=50*101=5050
5050*3=15150