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Radical din 5+7+9+....+2013-4×1005



Răspuns :

5+7+9+....+2013-4×1005 =
=5+(5+2)+(5+4)+(5+6)+....+(5+2008)-4020=
nr de 5      2008:2+1=1005
=5×1005+2(1+2+3+....+1004)-4020=
=5025+2×1004×1005/2-4020=
=1005+1004×1005=1005(1+1004)=1005×1005=1005²

√1005²=1005