What is the discriminant of 9x2 + 2 = 10x?
1. –356
2. –172
3. 28
4. 72

i got "28" like this (could you tell me if i'm right? ) :

9x^2 -10x + 2 =10x-10x
9x^2 - 10x +2 =0

a=9, b=-10, and c=2

insert into the equation: x = (-b +/- √b^2 -4ac)/2a

) +/- √-10^2 - 4(9)(2))/2(9) (10 +/- √100 - 72)/18

(10 +/- √28)/18 and since the discriminant is just the number under the radical, we don't have to go any further. 28 was the number did i get it right?