S1=2+4+6+......+100 S1=100+......+6+4+2 Adunand membru cu membru 2S1=102+....+102+102+102 S1 are 50 termeni 2S1=102*50 S1=102*50/2=102*25=2550 S2=1+3+5+.......+99 S2=99+....+5+3+1 Adunand membru cu membru 2S2=100+....+100+100+100(50 termeni) 2S2=100*50 S2=100*50/2=100*25=2500 S1-S2=S S=2550-2500=50 Cum se calculeaza termenii: (ultimul numar-primul numar):(din cat in cat cresc numerele)+1 (100-2):2+1=98:2+1=49+1=50 termeni (99-1):2+1=98:2+1=49+1=50 termeni Sper ca m-am facut inteles
