calculati
repede va rog


Calculatirepede Va Rog class=

Răspuns :

(1+3+5+...+79)/40 =(2-1+4-1+6-1+...+80-1)/40=[2(1+2+3+...+40)-1*80:2]/40=(2*40*41:2-40)/40=(40*41-40)/40=40(41-1)/40=41-1=40