Find Decreasing Intervals: y = -(x+10)² - 4 Quadratic Function

To find the interval where the function $y=-(x+10)^2-4$ is decreasing, we proceed as follows:

• Identify the Vertex: The given function is in the form $y = a(x-h)^2 + k$, where $a = -1$, $h = -10$, and $k = -4$. The vertex of the parabola is $(-10, -4)$.
• Determine the Parabola's Direction: Since $a = -1$, which is less than 0, the parabola opens downwards. This implies the function decreases as we move from the left of the vertex and increases as we move to the right of the vertex.
• Identify the Decreasing Interval: Because the parabola is opening downwards, the function is decreasing on the interval $x > -10$.

Therefore, the function is decreasing on the interval $x > -10$.

The correct multiple-choice answer is $x > -10$.