SOLUTION: -1, -3, -1, 5, 15 Find first differences for the sequence in order from a1 to a5. Determine whether or not the series is quadratic or not. A.) , 2, 6, 10; not quadratic B.) 2,

Algebra ->  Test -> SOLUTION: -1, -3, -1, 5, 15 Find first differences for the sequence in order from a1 to a5. Determine whether or not the series is quadratic or not. A.) , 2, 6, 10; not quadratic B.) 2,      Log On


   

Question 1081255: -1, -3, -1, 5, 15
Find first differences for the sequence in order from a1 to a5. Determine whether or not the series is quadratic or not.
A.) , 2, 6, 10; not quadratic
B.) 2, 2, 6, 10; quadratic
C.) -2, 2, 6, 10; not quadratic
D.) -2, 2, 6, 10; quadratic
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Calculate the first difference by subtracting,
d%5B1%5D=a%5B2%5D-a%5B1%5D=-3-%28-1%29=-3%2B1=-2
d%5B2%5D=a%5B3%5D-a%5B2%5D
d%5B3%5D=a%5B4%5D-a%5B3%5D
d%5B4%5D=a%5B5%5D-a%5B4%5D
Do the same for the remaining numbers.
.
.
.
Then calculate the second difference.
D%5B1%5D=d%5B2%5D-d%5B1%5D
D%5B2%5D=d%5B3%5D-d%5B2%5D
D%5B3%5D=d%5B4%5D-d%5B3%5D
If all the second differences are equal, the series is quadratic.
Else it is not.