If the relationship between x and y is quadratic,
which value of y completes the table?
x: -3 -1 1 3 5
y: 21 7 ? 27 61

A) 3
B) 7
C) 9
D) 17

Pls. explain why you picked that answer

The arithmetic sequence is 40, 47, 54 etc. In this case, the arithmetic difference is 7 and a1 being the first term is 40. Hence the arithmetic equation is an = 40 + 7*(n-1) where an is the nth term and n is an integer. Hence the answer to this problem is B.a_n = 40 + 7(n − 1) where n ≥ 1