Mindreko wrote:
Hi Karishma,
I'm not sure why you did this:
(2A - B = C) * 2
could you please explain why?
My own working for this qsn:
2A = B +C
5B = A + C
So 3A = 6B, and A = 2B
we need ratio of volumes of c to a+b
or c / a + b
We know A = 2B
We also know C = 2A - B
So C/A+B
2A-B/2B+B
4B-B/3B = 3B/3B = 1/1 or 1:1
Hope that helps.
The reason I multiplied the first equation by 2 is that I wanted to make the co-efficient of a and b equal.
I have two equations:
2A = B + C or 2A - B = C
5B = A + C or -A + 5B = C
I need C in terms of (A +B) so I need to make the coefficient of A and B equal.
If I add these two directly, I get A + 4B = 2C.
But if I multiply the first equation by 2 and then add, I get 3A + 3B = 3C. I tried to think of a way to make the co-efficients same. Just like you do when you solve equations simultaneously. It saves me the extra steps needed to find each variable in terms of another variable (the way you have done and got A and C in terms of B)
Here the co-efficient of A and B is same so 3(A+B) = 3C. I get C in terms of (A+B)
Obviously there is nothing wrong in what you have done. I just tried to save myself some steps and some time.