Answer:
The vertex of the function is the point ![(-3,-13)](https://tex.z-dn.net/?f=%28-3%2C-13%29)
The graph increase over the interval--------> (-3,∞)
Step-by-step explanation:
we have
![f(x)=6x-4+x^{2}](https://tex.z-dn.net/?f=f%28x%29%3D6x-4%2Bx%5E%7B2%7D)
<u>1) Convert to vertex form</u>
Group terms that contain the same variable, and move the constant to the opposite side of the equation
![f(x)+4=x^{2}+6x](https://tex.z-dn.net/?f=f%28x%29%2B4%3Dx%5E%7B2%7D%2B6x)
Complete the square. Remember to balance the equation by adding the same constants to each side
![f(x)+4+9=x^{2}+6x+9](https://tex.z-dn.net/?f=f%28x%29%2B4%2B9%3Dx%5E%7B2%7D%2B6x%2B9)
![f(x)+13=x^{2}+6x+9](https://tex.z-dn.net/?f=f%28x%29%2B13%3Dx%5E%7B2%7D%2B6x%2B9)
Rewrite as perfect squares
![f(x)+13=(x+3)^{2}](https://tex.z-dn.net/?f=f%28x%29%2B13%3D%28x%2B3%29%5E%7B2%7D)
-----> function in vertex form
<u>2) Find the vertex</u>
The vertex of the function is the point ![(-3,-13)](https://tex.z-dn.net/?f=%28-3%2C-13%29)
<u>3) Find the axis of symmetry</u>
we know that
In a vertical parabola, the axis of symmetry is equal to the x-coordinate of the vertex
The x-coordinate of the vertex in this problem is equal to ![x=-3](https://tex.z-dn.net/?f=x%3D-3)
therefore
the equation of the axis of symmetry is ![x=-3](https://tex.z-dn.net/?f=x%3D-3)
<u>4) Find the increase-decrease intervals</u>
The graph increase over the interval--------> (-3,∞)
The graph decrease over the interval--------> (-∞,-3)
see the attached figure to better understand the problem
<u>5) Find the x-intercepts of the function</u>
we know that
the x-intercepts are the values of x when the value of the function is equal to zero
In this problem the x-intercepts are
and ![(0.61,0)](https://tex.z-dn.net/?f=%280.61%2C0%29)
so
The function cross the x-axis twice
see the attached figure