x² -2·(a-1)·x -2a+1=0 .
x₁/x₂² +x₂/x₁² >= 1/x₁ +1/x₂ <=> x₁³ +x₂³ /x₁² ·x₂² >= x₁ +x₂ /x₁ ·x₂ <=> x₁³ +x₂³ /x₁ ·x₂ >= x₁ +x₂ <=> (x₁ +x₂)(x₁² -x₁·x₂ +x₂²) /x₁·x₂ >= x₁ +x₂ <=> x₁² -x₁·x₂ +x₂² /x₁·x₂ >= 1
<=> x₁² -x₁·x₂ -x₁·x₂ +x₂² >= 0 <=> (x₁ -x₂)² >= 0 ,care este adevarat pentru orice numere x₁,x₂∈R\{0} .