Please help I have a quiz soon

Answer:
The option that no represent a linear function is [tex]f(x)=3^x[/tex]
Step-by-step explanation:
we know that
The graph of a linear function is a straight line
The equation of a linear function in slope intercept form is equal to
[tex]f(x)=mx+b[/tex]
where
m is the slope
b is the y-intercept
Verify each case
option 1) we have
[tex]f(x)=3x-2[/tex]
This option represent a linear function
where
m=3
b=-2
option 2) we have
[tex]f(x)=x[/tex]
This option represent a linear function
where
m=1
b=0
This option represent a linear direct variation function
option 3) we have
[tex]f(x)=3^x[/tex]
This option not represent a linear function
This option represent a exponential function
option 4) we have
[tex]f(x)=3x[/tex]
This option represent a linear function
where
m=3
b=0
This option represent a linear direct variation function