Calculus 8th Edition

FALSE for example $x=2$ and the function, $f(x) = x^2$ $f(3\times x)=f(3\times 2)=f(6)=6^2=36$ and $3\times f(x)=3\times f(2)= 3\times 2^2=3\times4=12$ It disproves the statement. $f(3x)\ne 3f(x)$