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Feb 15 2018 07:26am
We are now starting to get into non-linear models of math in my course and it's a step above linear of course..

I'm wondering:

For example
Code
expand (2x+3)^2


So I then get 4x^2 + 2x * 3 + 3^2
Supposedly I left out a 2 in the equation that is supposed to be before the 2x

It's supposed to look like this:

4x^2 + 2 + 2x *3 + 3^2

Atleast that's what cymath says and it seems right. What am I doing wrong? Where does this "2" come from and how can I most easily start using these methods for when it's f.e (x-8)^2 or (x+6)^2

Thanks in advance!
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Feb 15 2018 08:03am
also one more question:

how can i convert per say: x^2 - 10^2 to (x+10)(x-10)? I don't see it. I want to know the right way to get it from ^2 form to () form or w/e it's called :lol:
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Feb 15 2018 08:49am
Basic rules :

(a + b)² = a² + 2ab + b²
(a - b)² = a² - 2ab + b²
(a + b)(a - b ) = a² - b²

See if it helps, and feel free to pm.

Good luck.

This post was edited by feanur on Feb 15 2018 08:49am
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Feb 15 2018 10:39am
Quote (xaz @ Feb 15 2018 09:03am)
also one more question:

how can i convert per say: x^2 - 10^2 to (x+10)(x-10)? I don't see it. I want to know the right way to get it from ^2 form to () form or w/e it's called :lol:


That's called difference of squares:
Code
a^2 – b^2 = (a + b)(a – b) or (a – b)(a + b)


Using your example:
Code
(x+10)(x-10) = x^2 - 10x + 10x - 100.

The -10x and +10x cancel out, so you're left with x^2 - 100.
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Feb 15 2018 01:59pm
Quote (feanur @ Feb 15 2018 04:49pm)
Basic rules :

(a + b)² = a² + 2ab + b²
(a - b)² = a² - 2ab + b²
(a + b)(a - b ) = a² - b²

See if it helps, and feel free to pm.

Good luck.


Yup got them down now.

Quote (Whiskers @ Feb 15 2018 06:39pm)
That's called difference of squares:
Code
a^2 – b^2 = (a + b)(a – b) or (a – b)(a + b)


Using your example:
Code
(x+10)(x-10) = x^2 - 10x + 10x - 100.

The -10x and +10x cancel out, so you're left with x^2 - 100.


Shit that looks so obvious when you put it that way :D
That was easy lol, but still I made it hard for me somehow
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Feb 15 2018 02:53pm
Quote (xaz @ Feb 15 2018 02:59pm)
Yup got them down now.



Shit that looks so obvious when you put it that way :D
That was easy lol, but still I made it hard for me somehow


:thumbsup:
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Feb 19 2018 06:56am
Question:
How is 3x^2 + 2x --> x(3x+2) when you break out the x out of the equation?

Someone please explain :)
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Feb 19 2018 12:28pm
Quote (xaz @ Feb 19 2018 08:56am)
Question:
How is 3x^2 + 2x --> x(3x+2) when you break out the x out of the equation?

Someone please explain :)


Is this not just using the distributive property of multiplication? Seems pretty straightforward to me.
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Feb 19 2018 12:42pm
Quote (Zpot @ 19 Feb 2018 12:28)
Is this not just using the distributive property of multiplication? Seems pretty straightforward to me.



Agreed.
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Feb 19 2018 12:44pm
Quote (Zpot @ Feb 19 2018 08:28pm)
Is this not just using the distributive property of multiplication? Seems pretty straightforward to me.


Quote (timmayX @ Feb 19 2018 08:42pm)
Agreed.


lol dude sorry, this was definately a stupid post from my side, I 100% regret typing it. I realized the second I wrote it why it is like that :rofl:

i know i'm the best mathematician
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