Answer:
F(3) - F(1) / (3-1)
(3^2 + 3*4 + 4) - (1^2 + 1*4 + 4) / (2)
(9+12+4) - (1+4+4) / (2)
(25)-(9)/(2)
(16)/(2)
8
Step-by-step explanation:
10365
12579 - 2214
= 10365
3 times 4
3 groups of 4...............