Mahery Raharinjatovo schrieb:
> Hello
> How can I solve this ?quation with Maxima ?
> 'diff(x,t)^2+5*x^2=8
Looking through the engineer's glasses, this is the sum of kinetic
energy and potential energy of a linear oscillator being constant. Thus
the time derivative shall vanish, which means a) potential energy
constant, x'(t)=0, or b) another, now linear DE of 2nd order describing
the motion of the oscillator, which you can solve easily.
(%i1) depends(x,t);
(%i2) de1: 'diff(x,t)^2+5*x^2=8;
(%i3) diff(de1, t);
de2: ratsimp(%/diff(x,t));
(%i5) de2sol: ode2(de2, x, t);
(%i6) de1;
subst(de2sol, de1);
ev(%, nouns);
trigsimp(%);
k1sol: solve(%, %k1);
(%i11) sol: subst( k1sol[2], de2sol);
s: part(sol,2);
(%i13) wxplot2d(subst([%k2 = 0], s), [t,0,12]);