First get the equation into the form: Ax^2 + Bx + C = 0 (the quadratic equation)..
We do this by subtracting 10x both sides (to get it on the other side)..
9x^2 + 2 = 10x
9x^2 - 10x + 2 = 10x - 10x
9x^2 - 10x + 2 = 0
Now the discriminant is: b^2 - 4ac
The quadratic equation is Ax^2 + Bx + C = 0
Here, A = 9, B = -10 and C = 2 so plug them in...
(-10)^2 - 4 (9)(2)
= 100 - 4 (18)
= 100 - 72
= 28 <--- answer...
