# Thread: Trying to make (x) the subject?

1. ## Trying to make (x) the subject?

I have;

3x - 2y = 1
4x + y 3

I think I get rid of the fraction and end up with;

3x - 2y
4x + y

Then I think;

3x - 2y = -4x + y

Then;

-2y + y = -4x + 3x
- y = x

therefore;

x = -y

Thanks

David

The above method didn't look right after posting?

3x - 2y = - 4x - y
4x + y = - 3x +2y
4x - 3x = x
y - 2y = -y

therefore;

x = - y

I think?

2. ## Re: Trying to make (x) the subject?

Originally Posted by David Green

3x - 2y = 1
4x + y 3
$\displaystyle \frac{3x-2y}{4x+y} = \frac{1}{3}$

Cross multiplying

$\displaystyle 3(3x-2y) = 1(4x+y)$

Expanding

$\displaystyle 9x-6y = 4x+y$

Grouping like terms

$\displaystyle 9x-4x = y+6y$

$\displaystyle 5x = 7y$

$\displaystyle x = \frac{7y}{5}$