It depends on what location the sun is setting. For example, in the east side of the North America, the sun may set near 7pm to 7:30pm now that we are in summer, but in Europe, the sum may set at 8pm
A = 6
tn = a + (n - 1)d
t4 = 6 + 3d = 12
3d = 12 - 6 = 6
d = 6/3 = 2
f(n + 1) = f(n) + 2
The zeroes are
0, -5, 3 + i (and its conjugate)
The factors are
x (x + 5) (x - (3 + i)) (x - (3 - i))
Expanding...
(x² + 5x)((x - 3) - i) ((x - 3) + i)
(x² + 5x)((x - 3)² - i²)
(x² + 5x)(x² - 6x + 9 - (-1))
(x² + 5x)(x² - 6x + 10)
x⁴ - 6x³ + 10x² + 5x³ - 30x² + 50x
x⁴ - x³ - 20x² + 50x
Just look it up on the web that will help a lot
