Answer:
sup(x,3)
Step-by-step explanation:
Linear equation:
A linear equation has the following format:
[tex]y = ax + b[/tex]
In a linear equation, when x changes by 1, y will always change by the amount a, which is called slope.
In this question:
y=sup(x,3)+2x+1
[tex]y = 2x + 1[/tex] would be a linear equation.
However, the expression sup(x,3), that is, the higher value between x and 3, means that the function is not linear.