Find the next two terms of the following sequence:

-21. -9, 11, 39

F(1)  = -21

F(2) = -9 = -21 + 4 x 3   = F(1) + 4 x (2^2 - 1)

F(3) = 11  = -21 + 4 x 8   = F(1) + 4 x (3^2 - 1)

F(4) = 39 = -21 + 4 x 15 = F(1) + 4 x (4^2 - 1)

...

F(n) = F(1) + 4 x (n^2 - 1)

=> F(5) = -21 + 4 x (5^2 - 1 ) = -21 + 4 x 24 = 75

=> F(6) = -21 + 4 x (6^2 - 1)  = -21 + 4 x 35 = 119

Hope this helps!

:)

the discriminant is 64 + 4*1*12 = 112

this is prime.

step-by-step explanation: