OCR C1 Completing the Square

Well $10 \neq 5$ even though it is divisible by 2. You don't need to find the roots.

What are you talking about?

1) It is important to use mathematical notation correctly. If you want to show something is divisible by two, factorise it.

2) Your method was tortuous. The answer could simply be stated.

Geez louise. I was only saying they were equal to 0 and you're going beserk.

I think I get what you mean Mr M! You can't just "divide by 2" because that's surely not right. You can factorise out the 2, but not just half everything?

EDIT: I was told the other week, that if you just do something like that, you generally lose an answer in quadratics especially.

I get $2(x-6)^2+8$

So would the line of symmetry be 6 because there's a -6 inside the bracket?

Some explain how they get the 8?

for 6(i) I got $2(x-6)^2+44$

How did you get 8?

for 6(i) I got $2(x-6)^2+44$

How did you get 8?

How did you get 44? You know you are supposed to take out the number inside the brackets are square it right? Then afterwards you either subtract on add to get to the original number on the outside.

I did $2(x^2 - 12x) + 80$
$2((x-6)^2 -36) + 80$

Fixed that for you.

or just use square brackets.

No-one answered the guy's question?

Basically from the completed square form you can see that the graph is a parabola, which is at its smallest (vertex) when x=6 (and at this point, y is 8).
So the line of symmetry is going to be the straight line through the vertex, ie x=6
The tangent is going to be the horizontal straight line that just touches the vertex, ie y=8

I did answer the question over one hour ago if you look back.

You didn't give any explanation, you just regurgitated the properties of the completed square form of an equation.
No offence

This is a new one on me. Elaborate?

None taken. I surrender confronted by your greater knowledge and experience.

This.



But it should be plus 8 not 80.