Answer:
D I'm sure....................... :D
Ya gotta use the Pythagorean theorem :)
a² + b² = c² (reminder: c is the hypotenuse)
4² + 8² = c²
16 + 64 = 80
√80 = 8.94
H = 8.94
we know that
arithematic sequence will always have common difference
(a)
−5, −7, −10, −14, −19, …
we can see that


they are not equal
so, this is not arithematic sequence
(2)
1.5, −1.5, 1.5, −1.5, …
we can see that


they are not equal
so, this is not arithematic sequence
(3)
4.1, 5.1, 6.2, 7.2, …
we can see that


they are not equal
so, this is not arithematic sequence
(4)
−1.5, −1, −0.5, 0, …
we can see that


they are equal
so, this is arithematic sequence