Question

Input x 2 output y=17, input x 4 output y=28, input x 6 output y=42, what is the rule for the table?

Answer 1

2 17
4 28
6 42

The points (2,17), (4,28), and (6,42) do not lie in a straight line, so the relations is not linear.
Let's assume they form a quadratic of the form
y = ax^2 + bx + c
subbing in the values, I get

4a + 2b + c = 17
16a + 4b + c = 28
36a + 6b + c = 42

start by subtracting pairs to eliminate the c, then solving for the remaining a and b

( I ended up with a=3/8, b=13/4, and c=9 )