Find the vertex:
Determine if the parabola will open up or down:
Since the value of a is positive, the parabola will open upwards
Find the x and y intercepts:
Factor to find the x intercepts
(x+8)(x+2)
x + 8 = 0
x = -8
x + 2 = 0
x = -2
x intercepts:
x = -2
x = -8
Find the y intercept
Hence, C. Graph A best represents the quadratic function
Answer:
[Vertex form]
Step-by-step explanation:
Given function:
We need to find the vertex form which is.,
where represents the co-ordinates of vertex.
We apply completing square method to do so.
We have
First of all we make sure that the leading co-efficient is =1.
In order to make the leading co-efficient is =1, we multiply each term with -3.
Isolating and
terms on one side.
Subtracting both sides by 15.
In order to make the right side a perfect square trinomial, we will take half of the co-efficient of term, square it and add it both sides side.
square of half of the co-efficient of term =
Adding 36 to both sides.
Since is a perfect square of
, so, we can write as:
Subtracting 21 to both sides:
Dividing both sides by -3.
[Vertex form]
