Answer question in image attached pls

Given are several terms in a quadratic pattern:

a1 = ?
a2 = 1
a3 = -16
a4 = ?
a5 = -14

let:

x       y
1       ?
2       1
3      -16
4       ?
5       -14

considering the 2nd term and 3rd term, we can determine a quadratic function:

y = -17x + 35

therefore,

a1 = 18
a4 = -33