can someone check this for me?

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- Dec 8th 2009, 07:01 PMwonderdcheck my work on quadratic equations?
can someone check this for me?

- Dec 8th 2009, 07:15 PMwonderd
what about this one?

- Dec 8th 2009, 07:20 PMBacterius
No, both are wrong (first one in the answer, second one in the writing) :(

In the first one, you must write both answers :

**and**

The second one has the correct answer but is not correctly written. Here is an example of how it should be written :

or

or

Thus

:)

EDIT : talking about the first question in this post ... - Dec 8th 2009, 07:24 PMpickslides
- Dec 8th 2009, 07:25 PMjgv115
You must show all your working

What if I didn't know what the quadratic formula was?

You're up to here:

The next bit is wrong. You didn't factor 2 out of the -4. - Dec 8th 2009, 07:25 PMBacterius
The other question you posted is wrong too :(

I am not taking account of the quadratic equation written on it because I do not see the link with the following.

Here is how you do it :

--> This is where you messed up : you did not factorize the .

Or, more conveniently :

- Dec 8th 2009, 07:37 PMwonderd
can someone help me understand the factorization part?

- Dec 8th 2009, 07:46 PMBacterius
Remember that . Here, you have :

This can be written :

The common factor is two, so you factorize it over the addition. Since you are factorizing all the (and not !), they become (some people prefer to remove them directly though) :

Now you can cancel out :

Which is simplified to :

Or, even more conveniently :

- Dec 8th 2009, 08:13 PMwonderd
still dont really folllow, sry

- Dec 8th 2009, 09:16 PMjgv115
alright let's break it down.

We have

if we had

we would factorise it by taking 2x out of the equation.

So we divide all terms by 2x:

So same as

we can take 2 out of the equation;

So divide everything by 2

you will get:

I divided the -4 by 2 (which made -2) and 2 by 2 ( which made 1)

Is this more clear now? - Dec 8th 2009, 09:59 PMwonderd
i think i got it now, thx a bunch

- Dec 9th 2009, 02:45 AMjgv115
Cool!