You are Here: Home >< Maths

# Vocab in a differntiation question c4 watch

1. In a pond the amount of pondeweed {P} grows at a rate proportional to the amount of pondweed already present in the pond. Pondweed is also removed by fish eating it at a constant rate of Q per unit of time.

Write a DE relating P and t.

So I have dP/dT = kP.

But where to go from the last part is it:

Q=dp/dt ?
2. How about dP/dT = kp - Q ?
3. (Original post by Mihael_Keehl)
In a pond the amount of pondeweed {P} grows at a rate proportional to the amount of pondweed already present in the pond. Pondweed is also removed by fish eating it at a constant rate of Q per unit of time.

Write a DE relating P and t.

So I have dP/dT = kP.

But where to go from the last part is it:

Q=dp/dt ?
Nah, it's
4. (Original post by khaleesi98)
How about dP/dT = kp - Q ?
(Original post by Zacken)
Nah, it's
So then Q is just a constant for which the population is decreasing by?
5. (Original post by Mihael_Keehl)
So then Q is just a constant for which the population is decreasing by?
Yes.
6. (Original post by Mihael_Keehl)
So then Q is just a constant for which the population is decreasing by?
Yes exactly ☺️
7. (Original post by Zacken)
Yes.
(Original post by khaleesi98)
Yes exactly ☺️
thnx

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 12, 2016
Today on TSR

### Edexcel C4 Maths Unofficial Markscheme

Find out how you've done here

### 2,327

students online now

Exam discussions

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams