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subst

eq: (yx+1)*(x^2-y)^2-...

subst(a,x^2-y,eq);

Calculate

subst

y=a*x;

x=t;

subst(x, t, a*x);

Calculate

subst

subst(2,x,x^2);

Calculate

subst

a1+a2*t+a3*(2*t*t-1);

subst((x-50)/70,t,t*t);

Calculate

subst-taylor

u=taylor(2*x/(1-x^2)+...

subst(0,x,x+1);

Calculate

subst

eq1: f=(p*W-q*L)*W*L;

eq2: W=100/350;

eq3: L=W;

Calculate

subst

eq1: h = m (s - P);

eq2: H = n (s - O);

eq3: y = u (x - h) + h;

Calculate

subst

expr: z^3 + (a1*z + a...

subst (expr, z, expr);

Calculate

subst

eq01:lambda=c/f;

eq02:f=E/h;

eq03:subst(eq02,eq01);

Calculate

subst

MA+(1/2*(l-a)+x)*F-F*x;

subst((l^2-a^2)*F/4/l...

subst(0,x,%);

Calculate

subst

Run Example
(%i1)derivabbrev:true ;
(%o1)                                true
(%i2) mainvar: t;
(%o2)                                  t
(%i3) x(t):= r(t)*sin(theta(t));
(%o3)                     x(t) := r(t) sin(theta(t))
(%i4) y(t):=r(t)*cos(theta(t));
(%o4)                     y(t) := r(t) cos(theta(t))
(%i5) xdot(t):= diff(x(t), t, 1);
(%o5)                     xdot(t) := diff(x(t), t, 1)
(%i6) ydot(t):= diff(y(t), t, 1);
(%o6)                     ydot(t) := diff(y(t), t, 1)
(%i7) xdotdot(t):= diff(xdot(t), t, 1);
(%o7)                  xdotdot(t) := diff(xdot(t), t, 1)
(%i8) ydotdot(t):= diff(ydot(t), t, 1);
(%o8)                  ydotdot(t) := diff(ydot(t), t, 1)
(%i9) thetadot(t):= diff(theta(t), t, 1);
(%o9)                 thetadot(t) := diff(theta(t), t, 1)
(%i10) thetadotdot(t) := diff(thetadot(t), t, 1);
(%o10)             thetadotdot(t) := diff(thetadot(t), t, 1)
(%i11) Assumption1: xdotdot(t)=0;
                                                                      2
(%o11) r(t) cos(theta(t)) theta(t)    - r(t) sin(theta(t)) (theta(t) )
                                  t t                               t
                  + 2 r(t)  cos(theta(t)) theta(t)  + r(t)    sin(theta(t)) = 0
                          t                       t       t t
(%i12) solve(Assumption1, r(t));
                 sin(theta(t)) r(t)    + 2 cos(theta(t)) theta(t)  r(t)
                                   t t                           t     t
(%o12) [r(t) = - -------------------------------------------------------]
                                                                      2
                 cos(theta(t)) theta(t)    - sin(theta(t)) (theta(t) )
                                       t t                          t
(%i13) Assumption2: ydotdot(t)=0;
                                                                        2
(%o13) - r(t) sin(theta(t)) theta(t)    - r(t) cos(theta(t)) (theta(t) )
                                    t t                               t
                  - 2 r(t)  sin(theta(t)) theta(t)  + r(t)    cos(theta(t)) = 0
                          t                       t       t t
(%i14) E1_1: subst(rdot(t), diff(r(t), t, 1), Assumption1);
                                                                      2
(%o14) r(t) cos(theta(t)) theta(t)    - r(t) sin(theta(t)) (theta(t) )
                                  t t                               t
                + 2 rdot(t) cos(theta(t)) theta(t)  + r(t)    sin(theta(t)) = 0
                                                  t       t t
(%i15) E1_2: subst(rdotdot(t), diff(diff(r(t), t, 1),t,1), E1_1);
                                                                      2
(%o15) r(t) cos(theta(t)) theta(t)    - r(t) sin(theta(t)) (theta(t) )
                                  t t                               t
             + 2 rdot(t) cos(theta(t)) theta(t)  + rdotdot(t) sin(theta(t)) = 0
                                               t
(%i16) E1_3: subst(rr(t), r(t), E1_2);
                                                                        2
(%o16) rr(t) cos(theta(t)) theta(t)    - rr(t) sin(theta(t)) (theta(t) )
                                   t t                                t
             + 2 rdot(t) cos(theta(t)) theta(t)  + rdotdot(t) sin(theta(t)) = 0
                                               t
(%i17) E1_4: solve(E1_3, rr(t));
                  2 rdot(t) cos(theta(t)) theta(t)  + rdotdot(t) sin(theta(t))
                                                  t
(%o17) [rr(t) = - ------------------------------------------------------------]
                                                                          2
                     cos(theta(t)) theta(t)    - sin(theta(t)) (theta(t) )
                                           t t                          t
(%i18) E1_5: subst(r(t), rr(t), E1_4[1]);
                2 rdot(t) cos(theta(t)) theta(t)  + rdotdot(t) sin(theta(t))
                                                t
(%o18) r(t) = - ------------------------------------------------------------
                                                                        2
                   cos(theta(t)) theta(t)    - sin(theta(t)) (theta(t) )
                                         t t                          t
(%i19) 
Run Example
n:4;
(%o1)                                  4
(%i2) m:m;
(%o2)                                  m
(%i3) subst([w=0],rat(diff((1+a*w+b*w^2)^m,w,n)));
       4  4        2        4   3        2       2         4   2
(%o3) a  m  + (12 a  b - 6 a ) m  + (12 b  - 36 a  b + 11 a ) m
                                                          2       2        4
                                                 + (- 12 b  + 24 a  b - 6 a ) m
(%i4) 
Run Example
n:2;
(%o1)                                  2
(%i2) m:m;
(%o2)                                  m
(%i3) subst([w=0],rat(diff(exp(a*w^2)^m,w,n)));
(%o3)                                2 a m
(%i4) 

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