which of these functions is linear?

Answer:
Step-by-step explanation:
y = 1x - 5 is the only function here that is linear.
Answer:
Function 2, y = x - 5
Step-by-step explanation:
Function 1 is called an Absolute Value Function (where there is absolute value symbol around the whole or a part of the equation, its parent function is; y = |x| )
Function 2 is called a Linear Function (which could be written as y = mx + b, here m and b are integer values, b value is the y-intercept, m is the slope)
Function 3 is called an Inverse Function ( where a value is divided by a variable like "x", it's parent function is; y = [tex]\frac{1}{x}[/tex] )
Function 4 is called a Quadratic Function (it's a function where the variable is squared, it's parent function is; y = x² )
Hope this helps!