To solve the equation \((x^2 + 2x + 2)(x^2 + 2x - 4) = -5\), we first set:
Let \(y = x^2 + 2x\). Then, the equation can be rewritten as:
\[ (y + 2)(y - 4) = -5 \]
Now, expanding the left-hand side gives us:
\[ y^2 - 4y + 2y - 8 = y^2 - 2y - 8 \]
Setting the equation equal to \(-5\):
\[ y^2 - 2y - 8 = -5 \]
Now, add 5 to both sides:
\[ y^2 - 2y - 3 = 0 \]
Next, we can solve this quadratic equation using the quadratic formula:
\[ y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
where \(a = 1\), \(b = -2\), and \(c = -3\):
\[ y = \frac{-(-2) \pm \sqrt{(-2)^2 - 4(1)(-3)}}{2(1)} \] \[ y = \frac{2 \pm \sqrt{4 + 12}}{2} \] \[ y = \frac{2 \pm \sqrt{16}}{2} \] \[ y = \frac{2 \pm 4}{2} \]
This results in two solutions for \(y\):
- \(y = \frac{6}{2} = 3\)
- \(y = \frac{-2}{2} = -1\)
Now, we will replace \(y\) back with \(x^2 + 2x\) and solve for \(x\):
- For \(y = 3\):
\[ x^2 + 2x = 3 \] \[ x^2 + 2x - 3 = 0 \]
Factoring gives:
\[ (x + 3)(x - 1) = 0 \]
So, \(x = -3\) or \(x = 1\).
- For \(y = -1\):
\[ x^2 + 2x = -1 \] \[ x^2 + 2x + 1 = 0 \]
This factors to:
\[ (x + 1)^2 = 0 \]
So, \(x = -1\) (with a multiplicity of 2).
Final Solutions
The solutions to the original equation \((x^2 + 2x + 2)(x^2 + 2x - 4) = -5\) are:
\[ x = -3, \quad x = 1, \quad x = -1 \text{ (with multiplicity 2)} \]