# 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.

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.

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

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

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

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

-Dan