-4n²-n-6=0
The discriminant is given by b^2 - 4ac = (-1)^2 - 4(-4)(-6) = 1 - 96 = -95
A discriminant < 0 means that we have non-real solutions
a = -4
b = -1
c = -6
The discriminant is always b2 - 4ac, so it's:
(-1)2 - 4(-4)(-6)
= 1 - 4(24)
= 1 - 96
= -95
If the discriminate is <0, the quadratic formula becomes unsolvable, which means there are no values of n which satisfy this equation.
A good resource to use is WolframAlpha when checking your answers for these problems.
Here is the site with this function as the input. You'll notice the graph never touches the x-axis which means that y can never equal zero and the problem has no solution.