To graph the equation \( y = -x^2 - 10x - 24 \), we can rearrange it as follows:
The standard form is already given as \( y = -x^2 - 10x - 24 \), which is a downward-opening parabola.
Step 1: Find the Vertex
The vertex of a parabola given in the form \( y = ax^2 + bx + c \) can be found using the formula:
\[ x = -\frac{b}{2a} \]
Here, \( a = -1 \), \( b = -10 \), and \( c = -24 \). Plugging these values into the formula gives:
\[ x = -\frac{-10}{2 \cdot -1} = \frac{10}{-2} = -5 \]
To find the y-coordinate of the vertex, substitute \( x = -5 \) into the equation:
\[ y = -(-5)^2 - 10(-5) - 24 = -25 + 50 - 24 = 1 \]
So, the vertex is at the point \( (-5, 1) \).
Step 2: Finding the Roots
To find the roots of the equation \( -x^2 - 10x - 24 = 0 \), we can set the equation to zero.
Rearranging gives:
\[ -x^2 - 10x - 24 = 0 \implies x^2 + 10x + 24 = 0 \]
Now we can either factor or use the quadratic formula:
\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
Here, \( a = 1, b = 10, c = 24 \):
\[ x = \frac{-10 \pm \sqrt{10^2 - 4 \cdot 1 \cdot 24}}{2 \cdot 1} = \frac{-10 \pm \sqrt{100 - 96}}{2} = \frac{-10 \pm \sqrt{4}}{2} = \frac{-10 \pm 2}{2} \]
Calculating the two roots:
- \( x = \frac{-10 + 2}{2} = \frac{-8}{2} = -4 \)
- \( x = \frac{-10 - 2}{2} = \frac{-12}{2} = -6 \)
Step 3: Identify Points on the Graph
Now we have the following important points:
- Vertex: \( (-5, 1) \)
- Roots: \( (-4, 0) \) and \( (-6, 0) \)
Step 4: Choose Additional Points
Let's choose two more points to fully represent the graph. We can evaluate the function at \( x = -7 \) and \( x = -3 \):
- For \( x = -7 \):
\[ y = -(-7)^2 - 10(-7) - 24 = -49 + 70 - 24 = -3 \quad \text{(Point: (-7, -3))} \]
- For \( x = -3 \):
\[ y = -(-3)^2 - 10(-3) - 24 = -9 + 30 - 24 = -3 \quad \text{(Point: (-3, -3))} \]
Summary of Points to Graph
The points to plot are:
- Vertex: (-5, 1)
- Root 1: (-4, 0)
- Root 2: (-6, 0)
- Point: (-7, -3)
- Point: (-3, -3)
Step 5: Graphing
You can plot these points on a Cartesian coordinate system. The parabola opens downward with roots at (-4, 0) and (-6, 0) and a vertex at (-5, 1).
Conclusion
The roots of the equation \( -x^2 - 10x - 24 = 0 \) are \( x = -4 \) and \( x = -6 \).