I'm getting a little confused with the quadrativ formula, i used to know it, but its been a while!

i'm getting -b+/- square root (b-4ac) / 2* c

the part im getting confused on is the 2 * c, what if my original equation was x^2 - 10x - 3 (where -3 would be c)

do i add the minus sign into the equation which would give me 2 * -3 = -6 and then divide the whole equation by -6 or do i forget the minus sign and change it to positive 6?