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?

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- Sep 4th 2008, 03:07 PMJulie03finite 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? - Sep 4th 2008, 03:38 PMskeeter
2nd differences are 2 , 3 , 4

3rd differences are a constant 1

it's cubic ...

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