The function f is defined by
[tex]f(x)=2x^2-3[/tex]To find f(3x), we would need to replace x in the function with 3x. This can be written as:
[tex]\begin{gathered} f(3x)=2(3x)^2-3 \\ f(3x)=2(9x^2)-3 \\ f(3x)=18x^2-3 \end{gathered}[/tex]Therefore, the answer is
[tex]f(3x)=18x^2-3[/tex]