Error, (in ODEtools/info) x(t) and x cannot both appear in the given ODE.

  • Thread starter Thread starter Susanne217
  • Start date Start date
  • Tags Tags
    Error Ode
Susanne217
Messages
311
Reaction score
0

Homework Statement



Hi I am trying to solve a seperable differential equation in Maple

eqn1:=diff(x(t),t)=3*t^2/sqrt(x);

But every time I type

dsolve(eqn1,x(t));

I get the very hurtfull error from Maple

"Error, (in ODEtools/info) x(t) and x cannot both appear in the given ODE."

What am I doing wrong?

I have changed it to

eqn1:=diff(x(t),t)=3*t^2/sqrt(x(t)); and Mapple accepted it...

Is this right?
 
Last edited:
Physics news on Phys.org
"x(t)" and "x" are different symbols. Maple is interpreting "x(t)" as a function of t and "x" as a constant. It appears to Maple that you are using "x" in two different ways and it will not allow that.
 
HallsofIvy said:
"x(t)" and "x" are different symbols. Maple is interpreting "x(t)" as a function of t and "x" as a constant. It appears to Maple that you are using "x" in two different ways and it will not allow that.

Okay why Hallsoftivy could they go ahead and write this in the error insteed :)

But thank you :)

I'm given the differential equation

\frac{dx}{dt} = \frac{3t^2}{\sqrt{x}}

without any initial conditions

the right way to solve this in Maple is the command:
eqn1:=diff(x(t),t)=3*t^2/sqrt(x(t));

??
 
Last edited:
? That's what I just said: Maple is telling you that you cannot use the letter "x" in two different meanings and that is how Maple is interpreting what you gave.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top