       Re: Problems with Solve

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• Subject: [mg132492] Re: Problems with Solve
• From: Unknown <dog at gmail.com>
• Date: Sun, 30 Mar 2014 04:42:11 -0400 (EDT)
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```On Sun, 23 Mar 2014 08:59:35 +0000, Ray Koopman wrote:

> 1. Use  NRoots[z + 5 (z^2 - 1) + 1 z^3 == 1, z], then pick the root you
> want.
>
> 2. B[s_?NumericQ] := Piecewise[{{Erfc[-x]+Erfc[y]-Erfc[z], s >= .5}},
> Erfc[-x]]
>
> ----- Samuel Mark Young <sy81 at sussex.ac.uk> wrote:
>> I'm trying to use the solutions of Solve from solving a cubic equation
>> - however, it keeps returning complex answers when there are real
>> solutions. For example:
>>
>> Solve[z + 5 (z^2 - 1) + 1 z^3 == 1, z]
>>
>> This equation has 3 real solutions. However, the answers returned when

Wow, I manually entered <1> to the rPi <creditCardSized computer>.
Amazing: but where's the syntax [without TOO much commercials] for my
free version of mathematica?

Why did the OP use "Solve"?
And how did the look-ma-no-hands-demo respondent [whithout any
elaboration/explanation to add value] know to use a different syntax?
And, within the context of <solutions of cubic equations>, what is
the meaning of "== 1, z"?

== TIA.

```

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