Verified answer

[tex] = 1x+3x²+3x+1 \\ \\ = 3 {x}^{2} + 4x + 1[/tex]

[tex]2x + 5 = 0 \\ \\ 2x = - 5 \\ \\ x = \frac{ - 5}{2} [/tex]

[tex] = 3 {x}^{2} + 4x + 1 \\ \\ = 3( \frac{ - 5}{2} )^{2} + 4( \frac{ - 5}{2} ) + 1 \\ \\ = 3( \frac{25}{4} ) - \frac{20}{2} + \frac{1}{1} \\ \\ = \frac{75}{4} - \frac{20}{2} + \frac{1}{1} \\ \\ = \frac{75 - 40 + 4}{4} \\ \\ = \frac{35 + 4}{4} \\ \\ = \frac{39}{4} \\ [/tex]

Answer:

39/4

Hope it's helpful!