Plecăm de la două numere identice, aaa și b:b:b:
a=b∣⋅aa=b \qquad | \cdot aa=b∣⋅a a2=a⋅b∣+a2a^2=a \cdot b \qquad | +a^2a2=a⋅b∣+a2 a2+a2=a⋅b+a2a^2 + a^2 = a\cdot b + a^2a2+a2=a⋅b+a2 2a2=a⋅b+a2∣−2ab2a^2 = a\cdot b + a^2 \qquad |-2ab2a2=a⋅b+a2∣−2ab 2a2−2ab=a2+ab−2ab2a^2-2ab = a^2+ab-2ab2a2−2ab=a2+ab−2ab 2a2−2ab=a2−ab2a^2-2ab = a^2-ab2a2−2ab=a2−ab 2a(a−b)=a(a−b)∣:(a−b)2a(a-b)=a(a-b) \qquad |:(a-b)2a(a−b)=a(a−b)∣:(a−b) 2a=a∣:a2a=a \qquad |:a2a=a∣:a 2=1.\boxed{2=1}.2=1.