SOLUTION: Find the Vertex I did the problem but I still dont really get how to do this that much and I dont know if this is right either. y = x2+6x+8 a=1 b=6

Question 188526: Find the Vertex

I did the problem but I still dont really get how to do this that much and I dont know if this is right either.
y = x2+6x+8 a=1 b=6

x= b = 6 = -6 = -3
_ _____ _ _____ ____
2a 2(1) 2

y = x2+6x+8
= 1(-3)2+6(-3)+8
= 9-18+8
= 1

Vertex= (-3 ,1 )

Found 2 solutions by feliz1965, jim_thompson5910:
Answer by feliz1965(151) (Show Source): You can put this solution on YOUR website!
To find the vertex, we need to find the value of x and y.
To find x, we use the formula x = -b/2a
We were given y = x^2 + 6x + 8
In the above function, a = 1 and b = 6
We plug that into the the formula given to find the value of x.
x = -b/2a
x = -6/2(1)
x = -6/2
x = -3
To find the value of y, we plug that value of x into the given function and solve for y.
y = (-3)^2 + 6(-3) + 8
y = 9 - 18 + 8
y = -9 + 8
y = -1
The vertex is the point (-3, -1).
By the way, this is a parabola opening upward.

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!

In order to find the vertex, we first need to find the x-coordinate of the vertex.

To find the x-coordinate of the vertex, use this formula: .

Start with the given formula.

From , we can see that , , and .

Plug in and .

Multiply 2 and to get .

Divide.

So the x-coordinate of the vertex is . Note: this means that the axis of symmetry is also .

Now that we know the x-coordinate of the vertex, we can use it to find the y-coordinate of the vertex.

Start with the given equation.

Plug in .

Square to get .

Multiply and to get .

Multiply and to get .

Combine like terms. Note: 9-18=-9 and -9+8=-1

So the y-coordinate of the vertex is .

So the vertex is .

So you were off by a sign.
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