Question

Over what interval is the graph of f(x) = -(X + 8)2 - 1 decreasing?

(-8,infinity)
(8,infinity )
(-infinity ,8)
(-infinity ,-8)

Answer 1

A.-8,infinity

Explanation:

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Answer 2

Function is decreasing on (-8,infinity)

Explanation:

The given function is
`f(x)=-(x+8)^2-1`

The first derivative is given by

`f'(x)=-2(x+8)`

For the function to be decreasing, we have

`f'(x)<0\\\\-2(x+8)<0`

Divide both sides by -2. Since, we are dividing by a negative number hence, the inequality sign will change.

`(x+8)>0`

Subtract 8 to both sides

`x>-8`

Therefore, the function is decreasing on (-8,infinity)

First option is correct.