Re: Solving equation and applying solution(s) expression.
- To: mathgroup at smc.vnet.net
- Subject: [mg84556] Re: Solving equation and applying solution(s) expression.
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 3 Jan 2008 20:29:49 -0500 (EST)
- Reply-to: hanlonr at cox.net
eqn = 3 x^2 - 2 x + 8 == 0;
expr = 3 x/(x^3 + 2);
soln = Solve[eqn, x]
{{x -> (1/3)*(1 - I*Sqrt[23])},
{x -> (1/3)*(1 + I*Sqrt[23])}}
Verifying that soln satifies eqn
eqn /. soln
{True,True}
Substituting soln into expr
FullSimplify[expr /. soln]
{(-(1/58))*I*(-79*I + Sqrt[23]),
(1/58)*I*(79*I + Sqrt[23])}
% // N
{-1.3620689655172413 -
0.08268675040194343*I,
-1.3620689655172413 +
0.08268675040194343*I}
Bob Hanlon
---- KP <MathematicaUser at gmail.com> wrote:
> Hi Everybody. I am a new subscriber to this group and looking forward
> to learning from folks who use Mathematica. I have a question and some
> help will be appreciated.....
>
> I want to solve an equation and then apply the solution(s) of the
> equation to an expression. For example, I want to solve 3 x^2 - 2 x +
> 8 =0. Then I want to apply the solutions to the expression 3 x / (x^3
> +2).
>
> The equation and the expression above are examples I used to
> illustrate my question. Please use the equation and the expression to
> help me out. Thank you and happy new year!
>
> --KP
>