Given the equation:
$$\left(x + 2\right)^{4} + \left(x + 2\right)^{2} - 12 = 0$$
Do replacement
$$v = \left(x + 2\right)^{2}$$
then the equation will be the:
$$v^{2} + v - 12 = 0$$
This equation is of the form
a*v^2 + b*v + c = 0
A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$v_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$v_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 1$$
$$b = 1$$
$$c = -12$$
, then
D = b^2 - 4 * a * c =
(1)^2 - 4 * (1) * (-12) = 49
Because D > 0, then the equation has two roots.
v1 = (-b + sqrt(D)) / (2*a)
v2 = (-b - sqrt(D)) / (2*a)
or
$$v_{1} = 3$$
Simplify$$v_{2} = -4$$
SimplifyThe final answer:
Because
$$v = \left(x + 2\right)^{2}$$
then
$$x_{1} = \sqrt{v_{1}} - 2$$
$$x_{2} = - \sqrt{v_{1}} - 2$$
$$x_{3} = \sqrt{v_{2}} - 2$$
$$x_{4} = - \sqrt{v_{2}} - 2$$
then:
$$x_{1} = - \frac{2}{1} + \frac{1 \cdot 3^{\frac{1}{2}}}{1} = -2 + \sqrt{3}$$
$$x_{2} = - \frac{2}{1} + \frac{\left(-1\right) 3^{\frac{1}{2}}}{1} = -2 - \sqrt{3}$$
$$x_{3} = - \frac{2}{1} + \frac{1 \left(-4\right)^{\frac{1}{2}}}{1} = -2 + 2 i$$
$$x_{4} = - \frac{2}{1} + \frac{\left(-1\right) \left(-4\right)^{\frac{1}{2}}}{1} = -2 - 2 i$$