Question

These tables represent a quadratic function with a vertex at (0,-1) what is the average rate of change for the interval from x=8 to x=9

Answer 1

Answer: -15

Explanation:

it was the right answer i got it wrong. but -15 was the right answer

Answer 2

From the information given the quadratic function is of the form,

`y=a(x-b)^2+c` which has vertex at
`(b,c)`

Since the vertex is
`(0,-1)`,
`b=0,c=-1`.

Thus the quadratic equation is
`y=ax^2-1`. Since
`y=ax^2-1` passes through
`(1,-2), (2,-5),..`, the equation of the quadratic function is
`y=-x^2-1`.

The rate of change in the interval
`(8,9)` is

`image`