This is the cubic formula (Excel friendly):
(((((((-b)^3)/(27*a^3))+((b*c)/(6*a^2))-(d/(2*a)))+(SQRT((((((-b)^3)/(27*a^3))+((b*c)/(6*a^2))-(d/(2*a)))^2)+((c/(3*a))-((b^2)/(9*a^2)))^3)))^(1/3))+((((((-b)^3)/(27*a^3))+((b*c)/(6*a^2))-(d/(2*a)))-(SQRT((((((-b)^3)/(27*a^3))+((b*c)/(6*a^2))-(d/(2*a)))^2)+((c/(3*a))-((b^2)/(9*a^2)))^3)))^(1/3)))-(b/(3*a))
Just copy and paste it into Word, go to find and replace, and replace a, b, and c with the corresponding cells on the Excel spreadsheet that you want to evaluate.
