Answer:
[tex]84x^{12}[/tex]
Step-by-step explanation:
[tex](4x)( - {3x}^{8} )( - {7x}^{3} ) \\ (4 \times - 3 \times - 7)( {x}^{} \times {x}^{8} \times {x}^{3} ) \\ (81)( {x}^{ 1 + 8 + 3} ) \\ 81 {x}^{12} [/tex]
