Răspuns:
a=1/2 ; b=2/3 ; c=5/4
c-b+a=³⁾5/4-⁴⁾2/3+⁶⁾1/2=15/12-8/12+6/12=13/12
c-a-b=³⁾5/4-⁶⁾1/2-⁴⁾2/3=15/12-6/12-8/12=1/12
produsul : 13/12·1/12=13/144
(c-b)²-a²=
(³⁾5/4-⁴⁾2/3)²-(1/2)²=
(15/12-8/12)²-(1/2)²=
(7/12)²-1/4=
49/144-³⁶⁾1/4=
49/144-36/144=13/144 diferenta
a=b
