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Re: How to solve the integrate problem

x>Q ,Q(P-W)-M(x-Q),  x belongs(Q,infinite)
x<=Q,P*x-W*Q+S(Q-x), x belongs(0,Q)

Q,P,W,M,S are unknown constant number.

I want to *dx*


It is not very clear, what do you mean by "I want to *dx*". If you need
to integrate your expression, try this:

(* This is your function *)

f[x_] := If[x > Q, Q (P - W) - M (x - Q), P*x - W*Q + S (Q - x)]

(* Here it is drawn with arbitrarily selected values of its parameters to see, how it looks like *)

Plot[f[x] /. {Q -> 1, P -> 2, W -> 1, M -> 1.5, S -> 3}, {x, 0, 3}]

(* Here the integral is calculated. It is a piecewise function and its value depends upon the value of Q *)
(* as well as upon the value xmax *)

 Integrate[f[x], {x, 0, xmax}, Assumptions -> Q >= 0], {xmax, 0, 2}]

If you want to calculate the derivative, consider this:

D[f[x], x]

If[x > Q, -M, P - S]

Have fun, Alexei

Alexei BOULBITCH, Dr., habil.
ZAE Weiergewan,
11, rue Edmond Reuter,
L-5326 Contern, LUXEMBOURG

Office phone :  +352-2454-2566
Office fax:       +352-2454-3566
mobile phone:  +49 151 52 40 66 44

e-mail: alexei.boulbitch at

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