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) + / - √-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 there ... Did I get it right?