[tex]x=\frac{1}{3}[/tex]
1) In this problem, the point is to find all values in each y=x.
2) So, let's do the following:
[tex]\begin{gathered} f(x)=4x-1 \\ \\ y=4x-1\:\:Plug\:y=x\:into\:that \\ \\ x=4x-1 \\ \\ x-4x=-1 \\ \\ -3x=-1 \\ \\ \frac{-3x}{-3}=\frac{-1}{-3} \\ \\ x=\frac{1}{3}\:\:Plug\:x=\frac{1}{3}\:into\:f(x)=4x-1\: \\ \\ y=4(\frac{1}{3})-1 \\ \\ y=\frac{4}{3}-1\:\:\:Rewrite\:1\;as\:a\:fraction \\ \\ y=\frac{4}{3}-\frac{3}{3} \\ \\ y=\frac{1}{3} \\ \end{gathered}[/tex]
2) Thus, we can tell that the answer is:
[tex]x=\frac{1}{3}[/tex]
Note: at x=1/3 y=1/3 what makes valid the condition f(x)=x
