To graph a linear function you need to determine two points of said function, plot them in the coordinates system and link them by a line.
The most easy point to find is the y-intersect. This is the value of y when x=0
Replace it in the equation:
[tex]\begin{gathered} y=3x-1 \\ y=3\cdot0-1 \\ y=-1 \end{gathered}[/tex]The y-intersect is (0, -1)
To determine the second point you have to select any value of x of your choise and replace it in the formula to determine the y-coordinate.
For example: x=4
[tex]\begin{gathered} y=3x-1 \\ y=3\cdot4-1 \\ y=11 \end{gathered}[/tex]The coordinates for the second point are (4, 11)
Now plot both points in the coordinate system and the line.
