# Thread: Simple algebra I have forgotten how to do

1. ## Simple algebra I have forgotten how to do

How do I get from 6x – 2(7y – 3x) to 12x - 14y?

I don't understand what I need to do with the numbers outside the brackets in relation to the numbers inside.

Thanks for le help

2. ## Re: Simple algebra I have forgotten how to do

$-2(7y-3x)$
$=(-2)\times{7y}+(-2)\times{-3x}$

Can you take it from there?

3. ## Re: Simple algebra I have forgotten how to do

Hi Quacky,

No I can't. I either go -2(7y-3x) = 14y+6x and then go 6x(-14y+6x) and multiply that out which is wrong. Or I take the 6x(7y-3x) = 42xy-18x^2 which is wrong again when combined with 14y+6x. So I have no idea lol. Any further help would be great

4. ## Re: Simple algebra I have forgotten how to do

Originally Posted by Quacky
$-2(7y-3x)$
$=(-2)\times{7y}+(-2)\times{-3x}$

Can you take it from there?
Originally Posted by JonathonDimblebee
Hi Quacky,

No I can't. I either go -2(7y-3x) = 14y+6x and then go 6x(-14y+6x) and multiply that out which is wrong. Or I take the 6x(7y-3x) = 42xy-18x^2 which is wrong again when combined with 14y+6x. So I have no idea lol. Any further help would be great
Starting where I left off:

$-2(7y-3x)$

$=(-2)\times{7y}+(-2)\times{-3x}$

$=-14y+6x$

The full expression you have been asked to simplify is $6x-2(7y-3x)$.

And we know that $-2(7y-3x)=-14y+6x$, so the problem becomes:

$6x-14y+6x$

5. ## Re: Simple algebra I have forgotten how to do

Wow that's simple. I wouldn't have came up with that in 1,000,000 years. Thanks for your time.

6. ## Re: Simple algebra I have forgotten how to do

Originally Posted by JonathonDimblebee
How do I get from 6x – 2(7y – 3x) to 12x - 14y?

I don't understand what I need to do with the numbers outside the brackets in relation to the numbers inside.

Thanks for le help
I suppose the confusing part is in the understanding that 6x is not part of - 2?

So -2(7y) = -14y and -2(-3x) = 6x, therefore;

6x - 14y + 6x