Rearranging a formula to make subject - Can someone please check my working?

[matheus]

Hey guys,

I have made an attempt at rearranging the formula below and I am looking for someone to just have a look over it and see if I got it right?

Really appreciate any pointers or tips

Thank you!

 

[Deleted member 4993]

Hey guys,

I have made an attempt at rearranging the formula below and I am looking for someone to just have a look over it and see if I got it right?

Really appreciate any pointers or tips

Thank you!

2a = b - c(b/3 - 4)

2a = b - cb/3 + 4c

6a = 3b - cb + 12c ← you had a mistake here

6(a - 2c) = b(3 - c) → we can divide both sides by (3-c) because (3-c)\(\displaystyle \ne\)0

b = 6(a - 2c)/(3 - c)

 

[matheus]

Hi guys,

Many thanks for the replies!

I am currently having another look at where I went wrong, I do struggle with these sorts of questions :-(

 

[Steven G]

Hey guys,

I have made an attempt at rearranging the formula below and I am looking for someone to just have a look over it and see if I got it right?

Really appreciate any pointers or tips

Thank you!

1) You should have know that something was wrong since you did not divide by c-3 or a multiple of c-3. The last line of your work is not finished as you can factor. You mistake was that you multiplied on term by 3 twice. Note that a(bc) is NOT ab*ac.

 

[lookagain]

Hey guys,

I have made an attempt at rearranging the formula below and I am looking for someone to just have a look over it and see if I got it right?

Really appreciate any pointers or tips

Thank you!

matheus,

from your second line to your third line, not only did you
multiply by 3 too many times, you did not distribute
the minus sign when removing the parentheses.

 

[matheus]

Hi guys,

Many many thanks for your helpful reply! I am always very grateful of this forum and its members for taking the time to help out people like me

 

[Steven G]

Mat, remember that when you have a term like -c(b/3 - 4),
deal with it right away: -bc/3 + 4c
Now, multiplying it by 3: -bc + 12c
Get my drift?

How many times do I need to tell you, it is not get my drift but rather get me a draft.

 

[Steven G]

Are you Sir Jonah's drinking buddy?

Actually I drink with A Wiles.