Răspuns:
(1+½+⅓+¼-½:½)×12/13=1
(1+½+⅓+¼-½:½)×12/13=1
(1+½+⅓+¼-1)×12/13=1 (1 se reduce cu -1)
(½+⅓+¼)×12/13=1 (aducem la acelasi numitor, 12)
(6/12+4/12+3/12)×12/13=1
13/12×12/13=1 (simplificăm 12 cu 12, 13 cu 13)
1=1
(1+1/2+1/3+1/4-1/2:0,5)×12/13=
=(1+1/2+1/3+1/4-1/2:1/2)×12/13=
=(1+1/2+1/3+1/4-1/2×2)×12/13=
=(1+1/2+1/3+1/4-1)×12/13=
=(1/2+1/3+1/4)×12/13=
=(6/12+4/12+3/12)×12/13=
=(10/12+3/12)×12/13=
=13/12×12/13=1
