simple Math prob. how to colculate?

[Stiletto]

Sups,
I'm sorry, but i dont know the english word for it, but i'm tryin to write a lil app which will colculate 'functions' like 2x*x + 5x + 3.
which goes like this:
x1,2 = (b*b something (-4)*a*c) /2
I hope u guys knows what i'm talkin about
well, my question is how can i colcuate the 'other' action of b*b?
sorry, bad english. PLZ CHECK attachment for a picture.
tnx!