If we have the function
[tex]f(x)=x^2[/tex]Then
[tex]\begin{gathered} f(x)+f(x)+f(x)=x^2+x^2+x^2 \\ =3x^2 \end{gathered}[/tex]This also can be written in the form
[tex]f(x)+f(x)+f(x)=3f(x)=3x^2[/tex]We see that both answer are the same, like it should be.