1. **State the problem:** Solve the quadratic equation $$x^2 + 8x = -4$$ for $x$.
2. **Rewrite the equation in standard form:** Move all terms to one side:
$$x^2 + 8x + 4 = 0$$
3. **Methods to solve quadratic equations:**
- **Factoring:** Try to express the quadratic as a product of two binomials.
- **Quadratic Formula:** Use the formula $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ where $a=1$, $b=8$, $c=4$.
- **Graphing:** Rewrite as a function $$f(x) = x^2 + 8x + 4$$ and find the $x$-intercepts.
- **Completing the Square:** Rewrite the quadratic in the form $$(x + d)^2 = e$$ and solve.
4. **Check if factoring works:**
We look for two numbers that multiply to $4$ and add to $8$. Since $4$ and $8$ do not factor nicely to satisfy this, factoring is not straightforward here.
5. **Quadratic Formula:**
$$x = \frac{-8 \pm \sqrt{8^2 - 4 \times 1 \times 4}}{2 \times 1} = \frac{-8 \pm \sqrt{64 - 16}}{2} = \frac{-8 \pm \sqrt{48}}{2}$$
Simplify $$\sqrt{48} = \sqrt{16 \times 3} = 4\sqrt{3}$$:
$$x = \frac{-8 \pm 4\sqrt{3}}{2}$$
Cancel common factor 2:
$$x = \frac{\cancel{2}(-4 \pm 2\sqrt{3})}{\cancel{2}} = -4 \pm 2\sqrt{3}$$
6. **Completing the Square:**
Start with $$x^2 + 8x + 4 = 0$$
Move constant:
$$x^2 + 8x = -4$$
Add $$\left(\frac{8}{2}\right)^2 = 16$$ to both sides:
$$x^2 + 8x + 16 = -4 + 16$$
$$ (x + 4)^2 = 12$$
Take square root:
$$x + 4 = \pm \sqrt{12} = \pm 2\sqrt{3}$$
Solve for $x$:
$$x = -4 \pm 2\sqrt{3}$$
7. **Graphing:**
Plotting $$y = x^2 + 8x + 4$$ and finding $x$-intercepts will give the same solutions.
**Answer:** The methods that work are: Using the Quadratic Formula, Rewriting as a function and graphing it, and Completing the Square Method. Factoring does not work easily here.
Quadratic Solving Methods 01Df53
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