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# C4 Differential Equations Help Needed. Watch

1. Not sure how to do 9(b) and how to start off Q10 in general. Question and working for 9(b) linked.

https://onedrive.live.com/redir?resi...hint=folder%2c
2. (Original post by TheKevinFang)
Not sure how to do 9(b) and how to start off Q10 in general. Question and working for 9(b) linked.

https://onedrive.live.com/redir?resi...hint=folder%2c
For 9b, why there is a 1/2 factor in the bracket?
is the rate of change. It's equal to the rate of gain - rate of loss. Write down the information given mathematically and change the subject.
3. (Original post by TheKevinFang)
Not sure how to do 9(b) and how to start off Q10 in general. Question and working for 9(b) linked.

https://onedrive.live.com/redir?resi...hint=folder%2c
If c and k are unknown constants then dividing them by two still gives an unknown constant... so I would say it's not necessary to write "c/2" and "k/2".
4. I don't think there's enough information given for Q9.
5. (Original post by Zacken)
I don't think there's enough information given for Q9.
Agreed.

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