Starting with the expression:
[tex]9x(3x-8)[/tex]Use the distributive property to expand the parenthesis:
[tex]=9x(3x)+9x(-8)[/tex]Multiply the expressions in each term to eliminate both parenthesis:
[tex]\begin{gathered} =9x\cdot3x-9x\cdot8 \\ =9\cdot3\cdot x\cdot x-9\cdot8\cdot x \\ =27x^2-72x \end{gathered}[/tex]Therefore:
[tex]9x(3x-8)=27x^2-72x[/tex]