In this case the answer is very simple.
Step 01:
Data
point 1 (0 , -1 )
point 2 (1 , 0)
point 3 (2, 3 )
point 4 (3 , 8)
Step 02:
Graph
y = x² - 1
The answer is:
The function is not linear. The relationship between the variable y and the variable x is quadratic.
