Find the intervals on which y = (x +4)^2 - 7 is increasing or decreasing

I have never had a problem like this i don't know what to do please help

thank you!

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- Aug 6th 2007, 12:41 PMaikenfanincreasing decreasing
Find the intervals on which y = (x +4)^2 - 7 is increasing or decreasing

I have never had a problem like this i don't know what to do please help

thank you! - Aug 6th 2007, 01:16 PMaikenfan
where did the 9 come from?

- Aug 6th 2007, 01:27 PMtopsquark
- Aug 6th 2007, 01:29 PMtopsquark
Actually there's a quicker way. A (vertical) parabola has the form:

$\displaystyle y = a(x - h)^2 + k$

where the vertex is at (h, k) and it opens upward if a > 0 and opens downward if a < 0.

So the vertex of $\displaystyle y = (x + 4)^2 - 7$ is at (-4, -7) and a = 1. Thus it opens upward. So it must be decreasing on $\displaystyle ( - \infty, -4)$ and increasing on $\displaystyle (-4, \infty)$.

-Dan