[tex]{ \boxed{\boxed{\begin{array}{cc} \maltese \bf \: given \: \\ \\ \rm \: d - \frac{1}{d} = 6 \\ \\ \bf \: now \\ \\ \rm {(d + \frac{1}{d} })^{2} = ( {d - \frac{1}{d} })^{2} + 4 \times d \times \frac{1}{d} \\ \\ = {6}^{2} + 4 \\ \\ = 36 + 4 \\ \\ = 40 \\ \\ \rm \: d + \frac{1}{d} = \pm \sqrt{40} \end{array}}}}[/tex]
