₪ ʎəɿʞɹɐq ₪
References :

Select Data - Data Validation…

in Allow Box Select - List
and in Source Box Type your choices separated by Comma.

Like:
- Yes,No
- A,B,C,D,E

or if you want to give advance choices then Enter the Formula in Source (Right down the 5 choices provided)

=OFFSET(B7,-5,0,5,1)

Note:
Replace B7 with Current cell’s Address (in which you want to get the choices)
replace -5 with the -4 or -3 as per Number of choices given
similarly fourth parameter 5 can be replaced with Number of choices given.

* Tip: Once you Apply Validation to one cell, you can copy the same validation to other cell.

for this copy the Cell (on which validation is already designed) and select the target cell and Right Click - Select Paste Special - Validation
and Click on OK (you are done)

Hope this will help you.

(*.*)a
References :
http://excelexpert.web.officelive.com
http://xlxpart.blogspot.com

http://en.wikipedia.org/wiki/Solvable_group

For cubics and quartics there are known solution methods but they get pretty hairy.

http://en.wikipedia.org/wiki/Cubic_function
http://en.wikipedia.org/wiki/Quartic_function

Of course if the degree is less than 3 then we have simple methods.

Other than that, in general you can do things like look for rational roots using the rational roots theorem, any obvious factorization, Descartes’ rule of signs, and numerical methods.
References :

This is undoubtedly why so many ‘category regulars’ have stock answers which they use to answer those questions that are asked over and over and over again.

If your ‘thorough answer’ is a good one … why not save it to use next time the question is asked?
References :