GCSE Maths changing the subject of the formula
hi guys,
Normally I can change the subject of a formula quite easily with not many problems however this one has really confused me and I cant do it. Can any one help me or give me the steps to do it?
The formula is
m/v-t/b=(m-t)/r *
I need to make m the subject
Thanks in advance for any help. it will be muchly appreciated
*The slashes are to indicate that its a fraction
Normally I can change the subject of a formula quite easily with not many problems however this one has really confused me and I cant do it. Can any one help me or give me the steps to do it?
The formula is
m/v-t/b=(m-t)/r *
I need to make m the subject
Thanks in advance for any help. it will be muchly appreciated
*The slashes are to indicate that its a fraction
(edited 9 years ago)
Scroll to see replies
Original post by cesca1u1u
i'm guessing..
m/v-t/b=(m-t)/r *
r(m/v - t/b) = m-t
r(m/v - t/b) +t =m
wait what did the * on the end mean?
m/v-t/b=(m-t)/r *
r(m/v - t/b) = m-t
r(m/v - t/b) +t =m
wait what did the * on the end mean?
it just referred to the comment about the slashes meaning a fraction
Original post by cesca1u1u
i'm guessing..
m/v-t/b=(m-t)/r *
r(m/v - t/b) = m-t
r(m/v - t/b) +t =m
wait what did the * on the end mean?
m/v-t/b=(m-t)/r *
r(m/v - t/b) = m-t
r(m/v - t/b) +t =m
wait what did the * on the end mean?
That hasn't made M the subject
Posted from TSR Mobile
Original post by indigo2011
it just referred to the comment about the slashes meaning a fraction
ohh right sorry haha
Original post by frances98
oh sorry didn't see that, let me try that again
Original post by frances98
I know, any ideas on a complete solution?
m/v-t/b=(m-t)/r *
m/v-(m-t)/r=t/b
mr/v-m+t=rt/b
m(r/v-1)=rt/b-t
m=(rt/b-t)/(r/v-1)
edit: copying error last line
m/v-(m-t)/r=t/b
mr/v-m+t=rt/b
m(r/v-1)=rt/b-t
m=(rt/b-t)/(r/v-1)
edit: copying error last line
(edited 9 years ago)
Original post by Stepidermis
m/v-t/b=(m-t)/r *
m/v-(m-t)/r=t/b
mr/v-m+t=rt/b
m(r/v-1)=rt/b-t
m=(rt/bt-t)/(r/v-1)
m/v-(m-t)/r=t/b
mr/v-m+t=rt/b
m(r/v-1)=rt/b-t
m=(rt/bt-t)/(r/v-1)
Thank you so much! I was so stumped, so glad to have an answer!
Original post by indigo2011
Thank you so much! I was so stumped, so glad to have an answer!
np
Here's my shout, not sure if it's right tbh
m/v - t/b = (m-t)/r [m]
mvbr/v - tvbr/b = vbr(m-t)/r
mbr - tvr = vb(m-t)
mbr = vb(m-t) + tvr
mbr = vbm - vbt + tvr
mbr - vbm = tvr - vbt
m(br-vb) = tvr - tvb
m = (tvr - tvb) / (br - vb)
Posted from TSR Mobile
m/v - t/b = (m-t)/r [m]
mvbr/v - tvbr/b = vbr(m-t)/r
mbr - tvr = vb(m-t)
mbr = vb(m-t) + tvr
mbr = vbm - vbt + tvr
mbr - vbm = tvr - vbt
m(br-vb) = tvr - tvb
m = (tvr - tvb) / (br - vb)
Posted from TSR Mobile
Original post by spurs9393
Here's my shout, not sure if it's right tbh
m/v - t/b = (m-t)/r [m]
mvbr/v - tvbr/b = vbr(m-t)/r
mbr - tvr = vb(m-t)
mbr = vb(m-t) + tvr
mbr = vbm - vbt + tvr
mbr - vbm = tvr - vbt
m(br-vb) = tvr - tvb
m = (tvr - tvb) / (br - vb)
Posted from TSR Mobile
m/v - t/b = (m-t)/r [m]
mvbr/v - tvbr/b = vbr(m-t)/r
mbr - tvr = vb(m-t)
mbr = vb(m-t) + tvr
mbr = vbm - vbt + tvr
mbr - vbm = tvr - vbt
m(br-vb) = tvr - tvb
m = (tvr - tvb) / (br - vb)
Posted from TSR Mobile
now i'm confused as i've got two different answers...both of which seem passable.
Original post by indigo2011
now i'm confused as i've got two different answers...both of which seem passable.
I honestly don't know if mines right, we're gonna need someone else to check. Is the question from a past paper or something you can check the answer from?
Posted from TSR Mobile
This question is A* rather than a low A or high B topic, because it requires anyone who is rearranging this to factor the subject out of the equation in order to separate everything. Since many of the explanations on here are correct, but do not give you an idea of what it would look like on paper:
Hope this helps.
*And trust me, this is the correct answer. If anyone needs any help with any topic or exam question in GCSE maths, PM me!
Hope this helps.
*And trust me, this is the correct answer. If anyone needs any help with any topic or exam question in GCSE maths, PM me!
(edited 9 years ago)
Original post by indigo2011
Normally I can change the subject of a formula quite easily with not many problems however this one has really confused me and I cant do it. Can any one help me or give me the steps to do it?
The formula is
m/v-t/b=(m-t)/r *
I need to make m the subject
Thanks in advance for any help. it will be muchly appreciated
*The slashes are to indicate that its a fraction[/ You basically find a common denominator which would be 'VBR', you then cancel the denominators with VBR step by step. 1st one, VBR-M/V, you could cancel the 'V' so it would be BR(m) and so on... That is the concept of the whole question, a decent 4 marks! I'm only a B grade student so i guess you can do this now mate
Posted from TSR Mobile
[QUOTE="Foji;55079627"]
There is no cancelling down fractions in rearranging the formula... You would simply approach it as if you're solving something, but for a different value.
Original post by indigo2011
hi guys,
Normally I can change the subject of a formula quite easily with not many problems however this one has really confused me and I cant do it. Can any one help me or give me the steps to do it?
The formula is
m/v-t/b=(m-t)/r *
I need to make m the subject
Thanks in advance for any help. it will be muchly appreciated
*The slashes are to indicate that its a fraction[/ You basically find a common denominator which would be 'VBR', you then cancel the denominators with VBR step by step. 1st one, VBR-M/V, you could cancel the 'V' so it would be BR(m) and so on... That is the concept of the whole question, a decent 4 marks! I'm only a B grade student so i guess you can do this now mate
Posted from TSR Mobile
Normally I can change the subject of a formula quite easily with not many problems however this one has really confused me and I cant do it. Can any one help me or give me the steps to do it?
The formula is
m/v-t/b=(m-t)/r *
I need to make m the subject
Thanks in advance for any help. it will be muchly appreciated
*The slashes are to indicate that its a fraction[/ You basically find a common denominator which would be 'VBR', you then cancel the denominators with VBR step by step. 1st one, VBR-M/V, you could cancel the 'V' so it would be BR(m) and so on... That is the concept of the whole question, a decent 4 marks! I'm only a B grade student so i guess you can do this now mate
Posted from TSR Mobile
There is no cancelling down fractions in rearranging the formula... You would simply approach it as if you're solving something, but for a different value.
Original post by spurs9393
I honestly don't know if mines right, we're gonna need someone else to check. Is the question from a past paper or something you can check the answer from?
Posted from TSR Mobile
Posted from TSR Mobile
Yes, of the answers that were posteed, yours was the correct one
Original post by Turtlebunny
Yes, of the answers that were posteed, yours was the correct one
Eh? mine also works, let t=1, v=2, r=3 and b=4 and see for yourself
Original post by Stepidermis
Eh? mine also works, let t=1, v=2, r=3 and b=4 and see for yourself
Nope, your answer does not work mathematically at all. While your answer may substitute correctly with certain numbers, your method produced the wrong answer. If you really want, I can post the marks scheme for this question.
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