# Quadratic Relations 1st 2nd differences

1. Oct 30, 2004

### rachelg2004

can someone help me

a) for each set of data, calculate the first differences and identify the linear and nonlinear relations
b) for the nonlinear relations determine the second differences and identify the quadratic relations

1)
x 5 6 8 11
y -2 -3 -5 -8

then it says to determine the slope

I DONT GET THIS AT ALL AND I"M SO FRUSTERATED! HELP!

2. Oct 30, 2004

### lalbatros

The first difference, probably, is simply the difference between successive numbers.

For the rest, the vocabulary used seems to be specific to your course. (note that I am french)
You should read the definitions and apply them.

If you want to post again the question, I suggest that you write also the definitions from your handbook.
Then, someone could explain you what it means.

I guess your question might be related to curve fitting, but I cannot be sure.
Indicate also the background to increase your chances to find some help.

3. Oct 30, 2004

### Alkatran

Linear relationship: The numbers always increase by the same value. Like:
2, 4, 6, 8, 10, 12 ...
or
5, 8, 11, 14, 17, 20 ...

Nonlinear: Hmmm, I wonder... maybe when it isn't constant?:
1,2,4,8,16
or
1,3,6,10,15

The slope is the difference on Y divided by the difference on X. For your answer, it's probably just something like:
(6 - 5) / 1 = 1