Answer:
x=1.3288 or -1.1288
Step-by-step explanation:
Given 
Subtract 4x from both sides

Since we can factor out 2 from whole equation, let's factor out 2.

Divide with 2 on both sides

We got the quadratic equation, we can solve for x using quadratic formula.





First, we are going to find the vertex of our quadratic. Remember that to find the vertex

of a quadratic equation of the form

, we use the vertex formula

, and then, we evaluate our equation at

to find

.
We now from our quadratic that

and

, so lets use our formula:




Now we can evaluate our quadratic at 8 to find

:




So the vertex of our function is (8,-72)
Next, we are going to use the vertex to rewrite our quadratic equation:



The x-coordinate of the minimum will be the x-coordinate of the vertex; in other words: 8.
We can conclude that:
The rewritten equation is

The x-coordinate of the minimum is 8
Step-by-step explanation:
6/10
divided by 2
3/10
divided by 1/2
3/5