1. **State the problem:** Solve the equation $$2y(y + 6) = 14$$ and find the solution set.
2. **Expand the left side:** Use the distributive property:
$$2y(y + 6) = 2y \cdot y + 2y \cdot 6 = 2y^2 + 12y$$
So the equation becomes:
$$2y^2 + 12y = 14$$
3. **Bring all terms to one side:** Subtract 14 from both sides:
$$2y^2 + 12y - 14 = 0$$
4. **Simplify the equation:** Divide the entire equation by 2 to make coefficients smaller:
$$\cancel{2}y^2 + \cancel{2} \cdot 6 y - \cancel{2} \cdot 7 = 0 \implies y^2 + 6y - 7 = 0$$
5. **Solve the quadratic equation:** Use the quadratic formula:
$$y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=1$, $b=6$, and $c=-7$.
6. **Calculate the discriminant:**
$$\Delta = b^2 - 4ac = 6^2 - 4 \cdot 1 \cdot (-7) = 36 + 28 = 64$$
7. **Find the roots:**
$$y = \frac{-6 \pm \sqrt{64}}{2 \cdot 1} = \frac{-6 \pm 8}{2}$$
8. **Calculate each solution:**
- For the plus sign:
$$y = \frac{-6 + 8}{2} = \frac{2}{2} = 1$$
- For the minus sign:
$$y = \frac{-6 - 8}{2} = \frac{-14}{2} = -7$$
9. **Solution set:**
$$\{1, -7\}$$
10. **Check the solutions:**
- For $y=1$:
$$2 \cdot 1 (1 + 6) = 2 \cdot 1 \cdot 7 = 14$$ (True)
- For $y=-7$:
$$2 \cdot (-7) (-7 + 6) = 2 \cdot (-7) \cdot (-1) = 14$$ (True)
Both solutions satisfy the equation.
**Final answer:** The solution set is $$\boxed{\{1, -7\}}$$.
Solve Quadratic 49D708
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