Here's one I've made for the same purpose:
Lbl ST
ClrHome
a+bi
fix 3
Prompt A,B,C
If A != 0
Then
((-B+SQROOT(B^2-4AC))/(2A)) -> Q
((-B-SQROOT(B^2-4AC))/(2A)) -> R
Disp Q>Frac, R>Frac
Real
Float
Else
If A=0
Then
Disp "TRY AGAIN"
Pause
Goto ST
It's longer, but more functional. This one will calculate imaginary values as well, displaying all results in fraction form if possible, otherwise rounding to 3 decimal places.
Explanation of symbols I used:
a+bi and Real can be found in the Mode menu, as can Fix 3 and Float.
!= means "not equal to" and can be found in the Test menu (2nd Math).
-> means "store as" and is the button right above the "On" key.
SQROOT is obviously the square root symbol, while ^2 is "squared"
The placement of parenthesis is critical, as I want the entire calculation to be done before storing the result as a variable, so make sure you use the right number of parenthesis at the right place.
EDIT: Crap, 2 weeks since the last post. Didn't realize that I was gravedigging here. It was only the fourth topic down, so I didn't bother to check the time of the last post. Sorry about that =/