Question

What type of function is this ? 15 points

Answer 1

1. quadratic polynomial
2. minimum at (1, -9)
3. decreasing on (-1, 1)

Explanation:

1. First differences in the y-values are ...

... -5-0 = -5; -8-(-5) = -3; -9-(-8) = -1; -8-(-9) = 1; -5-(-8) = 3; 0-(-5) = 5

Second differences are ...

... -3-(-5) = 2; -1-(-3) = 2; 1-(-1) = 2; 3-1 = 2; 5-3 = 2

These 2nd differences are constant, so the points can be described by a 2nd-degree polynomial.

2. Values on the graph range from 0 to a low of -9 and back up to 0. There is a minimum at (1, -9).

3. The value at x=-1 is -5; at x=1, it is -9, which is less than -5. The function is decreasing on the interval -1 to 1.