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Transposition

I need to make V1 the subject and im having trouble progressing with it

V1-Vs2/R1 + V1/R2 - IS = 0

I started doing this, is this correct?

R2V1 - R2VS + R1V1 / R1R2 = IS
Reply 1
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B_9710
18
Original post by lcuckstudent
I need to make V1 the subject and im having trouble progressing with it

V1-Vs2/R1 + V1/R2 - IS = 0

I started doing this, is this correct?

R2V1 - R2VS + R1V1 / R1R2 = IS


you need to use brackets so that the question is more clear because the way that you have written the question could mean a different few things
Reply 2
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lcuckstudent
OP
Original post by B_9710
you need to use brackets so that the question is more clear because the way that you have written the question could mean a different few things


(V1-Vs2 / R1) + (V1 / R2) - (IS) = 0

(R2V1 - R2VS + R1V1) / (R1R2) = IS

Does this help
Reply 3
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lcuckstudent
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Original post by lcuckstudent
(V1-Vs2 / R1) + (V1 / R2) - (IS) = 0

(R2V1 - R2VS + R1V1) / (R1R2) = IS

Does this help


I have attached a picture instead
20150910_212603.jpg512.9KB
Reply 4
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B_9710
18
All that you have done so far seems to be correct.
Reply 5
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B_9710
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Original post by lcuckstudent
I have attached a picture instead

Now multiply both sides of the equation by r1r2 and then try and see if you can take out v1 as a common factor which will allow you to further manipulate the equation and make v1 the subject of the equation.
Reply 6
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lcuckstudent
OP
Original post by B_9710
Now multiply both sides of the equation by r1r2 and then try and see if you can take out v1 as a common factor which will allow you to further manipulate the equation and make v1 the subject of the equation.


I think I may have run away with it to much
20150910_214616.jpg517.0KB
Reply 7
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B_9710
18
Original post by lcuckstudent
I think I may have run away with it to much

You're right. Now all you need to do is divide by sides by the (r2+r1) and then that's the answer.
Reply 8
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lcuckstudent
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Original post by B_9710
You're right. Now all you need to do is divide by sides by the (r2+r1) and then that's the answer.


Thats what I thought but I have been told the answer is the one attached
20150910_215545.jpg511.8KB
Reply 9
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B_9710
18
Original post by lcuckstudent
Thats what I thought but I have been told the answer is the one attached


It is exactly the same answer. The answer that you got originally though is in a much nicer form. You can easily show that these 2 fractions are identical.
Reply 10
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B_9710
18
image.jpg
Original post by B_9710
It is exactly the same answer. The answer that you got originally though is in a much nicer form. You can easily show that these 2 fractions are identical.


So my final outcome would be the one attached. But when I give the unknown variables a value, the results are not the same as the one I was told was correct
20150910_221217.jpg513.4KB
Reply 12
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B_9710
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Original post by lcuckstudent
So my final outcome would be the one attached. But when I give the unknown variables a value, the results are not the same as the one I was told was correct


It doesn't look like you have factorised the numerator correctly. You can only take out a factor of r2 on the numerator.
Original post by B_9710
It doesn't look like you have factorised the numerator correctly. You can only take out a factor of r2 on the numerator.


so your saying:

Is*R1*R2+R1*Vs

Cant be:

Is*R1(R2+Vs)

???
Reply 14
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B_9710
18
Original post by lcuckstudent
so your saying:

Is*R1*R2+R1*Vs

Cant be:

Is*R1(R2+Vs)

???


Yes because Is*R1 is not common to both. You could take out a factor of R1 giving R1(Is*R2 + Vs)
Original post by B_9710
Yes because Is*R1 is not common to both. You could take out a factor of R1 giving R1(Is*R2 + Vs)


But R1 is common to both R2 and Vs is it not im confused
Reply 16
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B_9710
18
Original post by lcuckstudent
But R1 is common to both R2 and Vs is it not im confused


R1 is common. But Is*R1 is not common to both which is what you originally did when you posted the picture.
Original post by B_9710
R1 is common. But Is*R1 is not common to both which is what you originally did when you posted the picture.


oh right yeah sorry I can see now!!!!

I think its getting late for me, thanks again for your help
Reply 18
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B_9710
18
Ok I've posted it all stow by step because it appears we have both lost our way with this one so I'll just do it from the start. image.jpg
Original post by B_9710
Ok I've posted it all stow by step because it appears we have both lost our way with this one so I'll just do it from the start. image.jpg


Yea great now when I plug this one and the other one with numbers they come out the same

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