Answer:

Step-by-step explanation:
Given

Required
The vertex
We have:

First, we express the equation as:

Where

So, we have:

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Take the coefficient of x: -1
Divide by 2: (-1/2)
Square: (-1/2)^2
Add and subtract this to the equation
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Expand

Factorize

Factor out x - 1/2




Compare to: 


Hence:

Answer:
B
Step-by-step explanation:
-2 is greater than -3
Answer:
x = 1 + i sqrt(7/2) or x = 1 - i sqrt(7/2)
Step-by-step explanation:
Solve for x:
2 x^2 - 4 x + 9 = 0
Divide both sides by 2:
x^2 - 2 x + 9/2 = 0
Subtract 9/2 from both sides:
x^2 - 2 x = -9/2
Add 1 to both sides:
x^2 - 2 x + 1 = -7/2
Write the left hand side as a square:
(x - 1)^2 = -7/2
Take the square root of both sides:
x - 1 = i sqrt(7/2) or x - 1 = -i sqrt(7/2)
Add 1 to both sides:
x = 1 + i sqrt(7/2) or x - 1 = -i sqrt(7/2)
Add 1 to both sides:
Answer: x = 1 + i sqrt(7/2) or x = 1 - i sqrt(7/2)