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# Helpp A Level Math (C4) Differential equations?! edexcel watch

1. Plz help with this maths question!!

'An object is moving so that its velocity is inversely proportional to its displacement at a fixed point. Write this as a differential equation, using k as the constant'
2. (Original post by family'sfailure)
Plz help with this maths question!!

'An object is moving so that its velocity is inversely proportional to its displacement at a fixed point. Write this as a differential equation, using k as the constant'
Velocity is dx/dt where x is displamenent.

So dx/dt = k/x.
3. Velocity is dx/dt where x is displamenent.

But how do you know that velocity is displacement with respect to time (dx/dt)?
4. (Original post by family'sfailure)
Plz help with this maths question!!

'An object is moving so that its velocity is inversely proportional to its displacement at a fixed point. Write this as a differential equation, using k as the constant'
Moved this to the Maths forum for you
5. (Original post by Zacken)
Velocity is dx/dt where x is displamenent.

So dx/dt = k/x.
Also as the general solution, I am getting

s = 2(kt+c)^0.5 which is wrong but I can't work out why?
6. (Original post by family'sfailure)
Velocity is dx/dt where x is displamenent.

But how do you know that velocity is displacement with respect to time (dx/dt)?
Not so formally: Speed=Distance/Time
7. (Original post by family'sfailure)
Also as the general solution, I am getting

s = 2(kt+c)^0.5 which is wrong but I can't work out why?
1. You should know that velocity is the rate of change of displacement with respect to time.

2. Why do you think what you've written is wrong?
8. (Original post by Zacken)
1. You should know that velocity is the rate of change of displacement with respect to time.

2. Why do you think what you've written is wrong?
This is on MyMaths so it marks the answer straight away and it says it's wrong
9. (Original post by family'sfailure)
This is on MyMaths so it marks the answer straight away and it says it's wrong
Send a picture of the question.
10. (Original post by Math12345)
Send a picture of the question.
11. (Original post by family'sfailure)
You entered which is not the same as .

.
12. (Original post by family'sfailure)
It's asking you to find the value of k...

You know that v = k/x so when v=2, x=3 means that 2 = k/3 means that k = 6.

Further to this, is not equal to .

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