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(Original title and post lost. Temporary title was "..................kk")

Posted 10 years ago

.k

POSTED BY: Ashley Lombardi

Hi,

not sure but this might help:

sol = DSolve[{x y'[x] + 2 y[x] == Sin[x], y[Pi/2] == 1}, y[x], x]

(* {{y[x] -> (-4 + \[Pi]^2 - 4 x Cos[x] + 4 Sin[x])/(4 x^2)}} *)

You can generate the graphs like so:

GraphicsColumn[{Plot[y[x] /. sol, {x, 0, 2}], 
  Plot[y[x] /. sol, {x, 0, 10}], Plot[y[x] /. sol, {x, 0, 100}]}]

enter image description here

You need to be careful on how to place the brackets, and which ones to use. Also use double equal signs for equations. Regarding the question about the initial value you might want to have a look at this:

GraphicsColumn[{Plot[{y[x] /. sol, 1}, {x, 0, 2}], 
  Plot[{y[x] /. sol, 1}, {x, 0, 10}], 
  Plot[{y[x] /. sol, 1}, {x, 0, 100}]}]

enter image description here

The initial condition is given where the horizontal line intersects with the blue curve. For the limits just type:

Limit[y[x] /. sol, x -> 0]

(* Infinity *)

and

Limit[y[x] /. sol, x -> Infinity]

(* 0 *).

Hope this helps, Marco

POSTED BY: Marco Thiel

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