Given the equation
$$2 \sin{\left(4 x \right)} = x 6 \sin^{2}{\left(2 \right)} - 1$$
transform
$$- 6 x \sin^{2}{\left(2 \right)} + 2 \sin{\left(4 x \right)} = 0$$
$$- x 6 \sin^{2}{\left(2 \right)} + 2 \sin{\left(4 x \right)} = 0$$
Do replacement
$$w = \sin{\left(2 \right)}$$
This equation is of the form
a*w^2 + b*w + c = 0
A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = - 6 x$$
$$b = 0$$
$$c = 2 \sin{\left(4 x \right)}$$
, then
D = b^2 - 4 * a * c =
(0)^2 - 4 * (-6*x) * (2*sin(4*x)) = 48*x*sin(4*x)
The equation has two roots.
w1 = (-b + sqrt(D)) / (2*a)
w2 = (-b - sqrt(D)) / (2*a)
or
$$w_{1} = - \frac{\sqrt{3} \sqrt{x \sin{\left(4 x \right)}}}{3 x}$$
$$w_{2} = \frac{\sqrt{3} \sqrt{x \sin{\left(4 x \right)}}}{3 x}$$
do backward replacement
$$\sin{\left(2 \right)} = w$$
substitute w: