V := x*y*z; A := 2*x*z + 2*y*z + x*y; k := 12000; z := k/(x*y); New_A := A; solve({diff(New_A,x), diff(New_A,y)},{x,y}); All := allvalues("); sol := All[1]; evalf(sol,3); grad(f(x,y),[x,y]) = t*grad(g(x,y),[x,y]); z := 'z': A := A; V := V; eq1 := diff(A,x) = t*diff(V,x); eq2 := diff(A,y) = t*diff(V,y); eq3 := diff(A,z) = t*diff(V,z); eq4 := V = k; solve({eq1,eq2,eq3,eq4},{x,y,z,t}); S := ": aS := allvalues(S);