If they represented a quadratic function, we'd be able to find coefficients a,b,c such that all pairs (x,y) from your table satisfy .

Pair (1,2) gives (1)

Pair (3,5) gives (2)

Pair (5,11) gives (3)

Pair (7,17) gives (4)

Subtracting (1) from (2) we get (5)

Subtracting (2) from (3) we get (6)

Subtracting (3) from (4) we get (7)

Subtracting (5) form (6) we get

Subtracting (6) form (7) we get

This means there's no solution, so the data can't be represented by a quadratic function.

The second part is illegible for me.