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# How do I solve dm/dt = R(1-A) - B (A) in MATLAB?

Asked by dafdfab on 19 Nov 2012

I have this equation:

```dm/dt = R(1-A) - B (A)
```

I need to solve A when:

```dmdt= 0
R =0.1
B= 0.2
```

I am able to solve it by hand, but how can I solve this problem in MATLAB? Can I set this as a function?

Jan Simon on 23 Nov 2012

@dafdfad: Destroying the question after an answer is given does not meet the intention of this forum. It is a counter-productive method. Please stop this.

Randy Souza on 29 Nov 2012

I have restored the original text of this question.

dafdfad, this question has a clear subject and an accepted answer, so it may be valuable to someone else in the future. If you have a good reason why it should be removed from MATLAB Answers, please flag the question, explain why it should be deleted, and an administrator or high-reputation contributor will consider deleting the question. Please do not simply edit your question away.

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Answer by Walter Roberson on 19 Nov 2012

If you have the symbolic toolbox,

```syms A
R = 0.1
B = 0.2
Asol = solve( R*(1-A)-B*A, A)
```

dafdfab on 19 Nov 2012

thank you soooo much walter

dafdfab on 19 Nov 2012

the answer given is right, but I am just having trouble understanding it. in the code dmdt did not appear at all, so the solve function automatically assume the whole equation equals to zero?

Walter Roberson on 19 Nov 2012

I left that part out as it is 0.

```syms A
R = 0.1
B = 0.2
dmdt = 0
Asol = solve( (R*(1-A)-B*A) - dmdt, A)
```