(%i125) (r-1)*(r+2)^2 = 16*t^2$
(%i126) rhs(last(solve(%,r)))$
(%i127) e : %-subst(t=-t,%)$
For real t, the expression e vanishes. Is there a way to get
Maxima to crunch it to zero? One term of factor(e)
looks like junk^(1/3) * mess^(1/3) - 1. And junk * mess = 1,
but what Maxima command does junk^(1/3) * mess^(1/3) ->
(junk * mess)^(1/3)?
Barton
PS. For a planet in parabolic orbit (inverse square law force),
the equation (r-1)*(r+2)^2 = 16*t^2 determines the radial distance
as a function of time.