[tex]x - 4 = 0 \\ \\ x = 4[/tex]

[tex] = 3x +2x² +4x³ \\ \\ = 3(4) + 2( {4)}^{2} + 4( {4)}^{3} \\ \\ = 12 + 2(8) + 4(64) \\ \\ = 12 + 16 + 256 \\ \\ = 284[/tex]

[tex]\begin{gathered}x - 4 = 0 \\ \\ x = 4\end{gathered}

[/tex]

[tex]\begin{gathered} = 3x +2x² +4x³ \\ \\ = 3(4) + 2( {4)}^{2} + 4( {4)}^{3} \\ \\ = 12 + 2(8) + 4(64) \\ \\ = 12 + 16 + 256 \\ \\ = 284\end{gathered} [/tex]