# Thread: System of Linear Equations

1. ## System of Linear Equations

Hi guys, I have scanned the question as its easier than typing it out and put it online here (sorry its kinda bad quality):

FreeImageHosting.net Hosting Service

If you guys cant see the image properly then tell me and I will try and clarify the problem.

Ok so my answers for question (i) is

I3 = 1 + (19/12)A
I2 = 1 + (5/4)A
I1 = 1 + (1/4)A

Is this right?

My answer for question (ii) is

A = 12

But can somebody show me how they would show that A = 12, if that is actually the right answer, and if not what is the right answer and how to get to it.

Thanks in advance

2. Originally Posted by Johnaloa
Hi guys, I have scanned the question as its easier than typing it out and put it online here (sorry its kinda bad quality):

FreeImageHosting.net Hosting Service

If you guys cant see the image properly then tell me and I will try and clarify the problem.

Ok so my answers for question (i) is

I3 = 1 + (19/12)A
I2 = 1 + (5/4)A
I1 = 1 + (1/4)A

Is this right?

My answer for question (ii) is

A = 12

But can somebody show me how they would show that A = 12, if that is actually the right answer, and if not what is the right answer and how to get to it.

Thanks in advance
Your currents are correct.

For the second part they give $I_2 - I_3 = 4 \implies I_3 - I_2 = -4$.

From the third current equation we have
$3(I_3 - I_2) = A$

So
$3 \cdot -4 = A = -12$

(Note: A negative current simply implies that the current flow is in the direction opposite that which you had assumed.)

-Dan