[tex] \frac{ {d}^{2} - 19d + 1}{(4d + 9)(4d - 9)} \\ (4d + 9)(4d - 9) = 0 \\ (d + \frac{9}{4} )(d - \frac{9}{4} ) = 0 \\ (d + 2.25)(d - 2.25) = 0 \\ d_{1} = - 2.25 \\ d_{2} = 2.25[/tex]