Find Decreasing Intervals for y = -x² + 10x - 16: Quadratic Function Analysis

The function provided is $y = -x^2 + 10x - 16$. We want to identify the intervals where this function is decreasing.

To do so, we first find the vertex of the parabola, which will help us determine the regions of increase and decrease. The vertex of a parabola given by $ax^2 + bx + c$ is located at $x = -\frac{b}{2a}$.

For our function, $a = -1$ and $b = 10$. Substituting these values into the formula, we calculate:

$x = -\frac{10}{2 \times -1} = \frac{10}{2} = 5$.

This means the vertex of the parabola is at $x = 5$. Since the coefficient of $x^2$ (i.e., $a$) is negative, the parabola opens downward. Consequently, the function decreases to the right of the vertex.

Thus, the interval where the function is decreasing is when $x > 5$.

Therefore, the solution to the problem is $x > 5$.