Complete Square 4B8186
1. **State the problem:** Solve the quadratic equation $2x^2 - 3x - 6 = 0$ by completing the square.
2. **Rewrite the equation:** Divide all terms by 2 to make the coefficient of $x^2$ equal to 1:
$$x^2 - \frac{3}{2}x - 3 = 0$$
3. **Isolate the constant term:**
$$x^2 - \frac{3}{2}x = 3$$
4. **Complete the square:** Take half of the coefficient of $x$, which is $-\frac{3}{2}$, half is $-\frac{3}{4}$, then square it:
$$\left(-\frac{3}{4}\right)^2 = \frac{9}{16}$$
Add this to both sides:
$$x^2 - \frac{3}{2}x + \frac{9}{16} = 3 + \frac{9}{16}$$
5. **Rewrite the left side as a perfect square:**
$$\left(x - \frac{3}{4}\right)^2 = \frac{48}{16} + \frac{9}{16} = \frac{57}{16}$$
6. **Take the square root of both sides:**
$$x - \frac{3}{4} = \pm \sqrt{\frac{57}{16}} = \pm \frac{\sqrt{57}}{4}$$
7. **Solve for $x$:**
$$x = \frac{3}{4} \pm \frac{\sqrt{57}}{4} = \frac{3 \pm \sqrt{57}}{4}$$
**Final answer:**
$$x = \frac{3 + \sqrt{57}}{4} \quad \text{or} \quad x = \frac{3 - \sqrt{57}}{4}$$