# Question:How do I solve the following system of differential equations?

## Question:How do I solve the following system of differential equations?

Hey there i try to solve this system of equations. It is required that the left side of the equation only take positive values. Has someone an idea to fix this solution or has maybe another idea to help me.

> m[1] := 30; c[1] := 48000; c[0] := 20000; d[1] := 21; d[0] := 70;

> DGL1 := m[1]*(D(D(x)))(t)+d[0]*(D(x))(t)+d[1]*(D(x))(t)+c[0]*x(t)+c[1]*x(t)+50000 = -(1/1000)*c[1]*S-(1/1000)*d[1]*DS*((1/60)*(2*Pi*250))-(1/1000)*m[1]*DDS*((1/60)*(2*Pi*250))^2;

> GL1 := eval(m[1]*D((D(x))(t))+d[0]*(D(x))(t)+d[1]*(D(x))(t)+c[0]*x(t)+c[1]*x(t)+50000 = -(1/1000)*c[1]*S-(1/1000)*d[1]*DS*((1/60)*(2*Pi*250))-(1/1000)*m[1]*DDS*((1/60)*(2*Pi*250))^2, x(t) = sign(c[1])*y(t)^2);

> init := x(1.1) = 1, (D(x))(1.1) = .2;

> A := dsolve({GL1, x(1.1) = 1, (D(x))(1.1) = .2});
%;
Error, (in unknown) invalid input: op expects 1 or 2 arguments, but received 0
> F := dsolve({GL1, init}, numeric);
%;
Error, (in unknown) invalid input: op expects 1 or 2 arguments, but received 0

﻿