The Student Room Group

Help with the "changing the subject of a formula"?

How is this one done?

A = B/B-C (subject: B)
(edited 6 years ago)

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Original post by Darth_Memo_
How is this one done?

A = B/B-C


What do you want the subject to be?
I'm assuming the subject you want is B?
To confirm, your equation is A=BBC A = \frac {B}{B-C} ?

What are your first thoughts?
(edited 6 years ago)
Reply 3
Original post by TheMindGarage
What do you want the subject to be?


"B"
Reply 4
Original post by JaredzzC
I'm assuming the subject you want is B?
To confirm, your equation is A=BBC A = \frac {B}{B-C} ?

What are your first thoughts?


Yes this is the equation
Factorisation is included in the process. Have a solid look at the question
Original post by Darth_Memo_
Yes this is the equation


You need B as the subject, but you can't do it at the moment since it's part of the fraction and it has the expression BC B-C on the denominator.

You first step is to think about how you would go about solving the issue with the fraction.
Reply 7
B=(AC)/(A-1) is the final answer so you can work backwards from that.
(edited 6 years ago)
Reply 8
AB - AC = B
AB - B = AC
just a bit of a hint...this is how to start it off
Original post by LRxS
A(B-C)=B

x

I did fail maths last year though so you may want to check 😂


Please do not post full solutions.
Your help is appreciated but providing the OP with the full solutions is not permitted.

Providing hints so that they are able to solve the problem with our guidance is the most beneficial way for them to learn.

Here are the posting guidelines so you can familiarise yourself with them: https://www.thestudentroom.co.uk/showthread.php?t=4919248
(edited 6 years ago)
Original post by LRxS
A(B-C)=B

I did fail maths last year though so you may want to check 😂

Just so you know, full solutions are generally not allowed as per the posting guidelines at the top of this forum. :smile:.
Original post by LRxS
A(B-C)=B

AB-AC=B

AB=B+AC

AB-B=AC

B(A-1)=AC

B=(AC)/(A-1)

I did fail maths last year though so you may want to check 😂


to be fair...
Original post by LRxS
A(B-C)=B

AB-AC=B

AB=B+AC

AB-B=AC

B(A-1)=AC

B=(AC)/(A-1)

I did fail maths last year though so you may want to check 😂


This is right but why would u tell them the answer. U could have helped them thru it so they can understand the problem instead of spoon-feeding them.:s-smilie:
Reply 13
Original post by JaredzzC
Please do not post full solutions.
Your help is appreciated but providing the OP with the full solutions is not permitted.

Providing hints so that they are able to solve the problem with our guidance is the most beneficial way for them to learn.


Not permitted, or not advised?
OP is clearly struggling and actually a worked solution is an excellent thing to learn from, as it shows the OP all the stages, allowing them to apply it to similar problems in the future.
Reply 14
Original post by hsalika
This is right but why would u tell them the answer. U could have helped them thru it so they can understand the problem instead of spoon-feeding them.:s-smilie:


Tbh worked examples have always helped me massively. Sometimes it’s the best way to learn.
Original post by LRxS
Not permitted, or not advised?
OP is clearly struggling and actually a worked solution is an excellent thing to learn from, as it shows the OP all the stages, allowing them to apply it to similar problems in the future.


I attached the posting guidelines link to my previous post.

You have not even given them the opportunity to respond and provide their thoughts of how they would tackle the question.

We are here to assist them, not do it for them.
If they are struggling, we provide them with hints.
If they are still struggling, we will provider them with bigger hints so that they can proceed with the question.
Reply 16
@JaredzzC @Paulington @hsalika I’ve revised my original reply to this thread so it’s less “spoonfed”. I still maintain though that sometimes a worked solution is the best way to learn.
Reply 17
Original post by JaredzzC
I attached the posting guidelines link to my previous post.

You have not even given them the opportunity to respond and provide their thoughts of how they would tackle the question.

We are here to assist them, not do it for them.
If they are struggling, we provide them with hints.
If they are still struggling, we will provider them with bigger hints so that they can proceed with the question.


You hadn’t attached them to your original post, presumably an edit, so I hadn’t seen that link when I replied. I’ve had a brief read. I’m literally never in the maths forum and I use the app - this simply showed up on “Latest”, I think, so I wasn’t even sure what forum it might be in.

I’ve revised my original post, hopefully you’re happy with it now.
Original post by LRxS
You hadn’t attached them to your original post, presumably an edit, so I hadn’t seen that link when I replied. I’ve had a brief read. I’m literally never in the maths forum and I use the app - this simply showed up on “Latest”, I think, so I wasn’t even sure what forum it might be in.

I’ve revised my original post, hopefully you’re happy with it now.


Thank you. I agree that it can be a way to learn, but it's not the philosophy that we should be using.

In regards to the link, it was added as an edit although this was before I had mentioned it in my comment so that it would be available, should you have read it/scrolled through it again.

Sorry, I may have been slightly forward with my response. We genuinely do appreciate your help and please do continue to provide assistance!

It's all about developing the student's ability to solve the problem and having a greater understanding of the underlying concepts.

This is best done when we are able to assist them in getting to the final solution and I personally think they would remember it more having done it themselves, so it serves as a reference for similar problems they come across in the future.

My apologies again, it was an overreaction but it was more due to not being able to assist the OP in the most beneficial way, as opposed to a personal attack on you.

I hope to see you around more in these forums :smile:

All the best.
Reply 19
Original post by JaredzzC
Thank you. I agree that it can be a way to learn, but it's not the philosophy that we should be using.

In regards to the link, it was added as an edit although this was before I had mentioned it in my comment so that it would be available, should you have read it/scrolled through it again.

Sorry, I may have been slightly forward with my response. We genuinely do appreciate your help and please do continue to provide assistance!

It's all about developing the student's ability to solve the problem and having a greater understanding of the underlying concepts.

This is best done when we are able to assist them in getting to the final solution and I personally think they would remember it more having done it themselves, so it serves as a reference for similar problems they come across in the future.

My apologies again, it was an overreaction but it was more due to not being able to assist the OP in the most beneficial way, as opposed to a personal attack on you.

I hope to see you around more in these forums :smile:

All the best.


Don’t apologise! I’m the one who hadn’t read the rules 😂

As for seeing more of me here... somewhat unlikely 😂 I failed AS maths & now avoid it with a passion.....

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