# finite differences to find out if it is linear or quadratic

• September 4th 2008, 03:07 PM
Julie03
finite differences to find out if it is linear or quadratic
how do you use finite differences to determine whether relation is quadratic or linear?

X, Y FIRST DIFFERENCE

(1,-33) -

(2,-31) 2

(3,-27) 4

(4,-20) 7

(5,-9) 11

Is this relation linear, quadratic OR neither and why?
• September 4th 2008, 03:38 PM
skeeter
2nd differences are 2 , 3 , 4

3rd differences are a constant 1

it's cubic ...

$y = \frac{x^3}{6} + \frac{5x}{6} - 34$