Christian,
Welcome to Maxima!
test():=
> block([x,y],
> eq1:x^2+3*x+1,
> solve(eq1,x),
> plot2d(eq1,[x,0,3]),
> );
A block returns the *last* value. In this case, that would be the return
value of the "plot2d" functions, which is not very interesting. To return
the list of solutions, try:
test():=
> block([x,y],
> eq1:x^2+3*x+1,
> sols: solve(eq1,x),
> plot2d(eq1,[x,0,3]),
> sols );