How do you tell whether the graph opens up or down, find the vertex, and find the axis of symmetry given #y=-2x^2-6x+3#?
1 Answer
Opens Down
Vertex: (-
Axis of Symmetry: x=-
Explanation:
So one of the easiest ways you can find this information is by graphing. The axis of symmetry will always be a vertical line for a quadratic equation, so it will always be x= (x value of the vertex)
Let's start from the basics,
Standard form, a
The a value determines whether the parabola is face up or down. A negative 'a' value, such as -2, makes the parabola open down, whereas a positive 'a' value like 2, will make the parabola open up.
To find the vertex of a quadratic function, first calculate
So
Now for the 'y' value of the vertex, simply substitue
So, -2
This simplified gives you -
Add the numbers together, and you should get
So your vertex is (-
Hope this clarifies things!