Question

a+1 = 5
    a
   a² + 1 = ?
          a

Answer 1

$a+ \frac{1}{a} =5 \\ a^{2} + \frac{1}{ a^{2} } =? \\ (a+ \frac{1}{a}) ^{2} = 5^{2}$
$a^{2} + \frac{1}{ a^{2} } +2*a* \frac{1}{a} =25 \\ a^{2} + \frac{1}{ a^{2} } =25-2 \\ a^{2} + \frac{1}{ a^{2} } =23$