Question: two numbers add to $\frac{1}{4}$ and multiply to $-\frac{1}{8}$
1. **State the problem:** Find two numbers whose sum is $\frac{1}{4}$ and whose product is $-\frac{1}{8}$.
2. **Use the quadratic equation approach:** Let the two numbers be $x$ and $y$. We know:
$$x + y = \frac{1}{4}$$
$$xy = -\frac{1}{8}$$
3. **Form a quadratic equation:** If $x$ and $y$ are roots of the quadratic equation, then the equation is:
$$t^2 - (x+y)t + xy = 0$$
Substitute the known sums and products:
$$t^2 - \frac{1}{4}t - \frac{1}{8} = 0$$
4. **Solve the quadratic equation:** Use the quadratic formula
$$t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=1$, $b=-\frac{1}{4}$, and $c=-\frac{1}{8}$.
Calculate the discriminant:
$$\Delta = \left(-\frac{1}{4}\right)^2 - 4 \times 1 \times \left(-\frac{1}{8}\right) = \frac{1}{16} + \frac{1}{2} = \frac{1}{16} + \frac{8}{16} = \frac{9}{16}$$
5. **Find the roots:**
$$t = \frac{-\left(-\frac{1}{4}\right) \pm \sqrt{\frac{9}{16}}}{2 \times 1} = \frac{\frac{1}{4} \pm \frac{3}{4}}{2}$$
Calculate each root:
- For the plus sign:
$$t = \frac{\frac{1}{4} + \frac{3}{4}}{2} = \frac{1}{2}$$
- For the minus sign:
$$t = \frac{\frac{1}{4} - \frac{3}{4}}{2} = \frac{-\frac{1}{2}}{2} = -\frac{1}{4}$$
6. **Answer:** The two numbers are $\frac{1}{2}$ and $-\frac{1}{4}$.