Answer: Nonlinear
Step-by-step explanation:
The variable x increases by 1 each time we move down the rows. This increase is constant or the same jump each time.
However, the variable y increases by different amounts. From y = 2 to y = 6, we have +4. Then from y = 6 to y = 12 is +6. This mismatch of increases is sufficient to prove we don't have a linear function. The function is nonlinear.
Visually, we can plot all of the points on the same xy grid. Notice that a straight line does not go through all four points. Rather, a parabola does, and the equation of the parabola is y = x^2+x which is the same as y = x(x+1).