Math Help - Application Product Rule

1. Application Product Rule

Determine the point(s) on the curve that correspond to the given slope of the tangent.

y = (2x-1)(-4+x^2), m=3
y' = 6x^2 - 2x - 8

Set y' = 3
3 = 6x^2 - 2x - 8
0 = 6x^2 - 2x - 5

Now what do I do. I used the quadratic formula to get x-intercepts:
[2+- sqrt(124)]/12

But these do not end up being the correct x values for the two points on this function??

Can someone help me, thanks.

2. $6x^2 - 2x - 8 = 3$

$6x^2 - 2x - 11 = 0$

try again ...