1. **State the problem:** We need to solve the quadratic equation $$y = -7 \times 10^{-6} x^2 + 0.0028 x + 0.0899$$ for $x$ given different values of $y$: 0.1, 0.0855, 0.0845, 0.089, 0.086, 0.086, 0.085, 0.0805.
2. **Formula used:** The quadratic equation in standard form is $$ax^2 + bx + c = 0$$ where here $$a = -7 \times 10^{-6}, b = 0.0028, c = 0.0899 - y.$$ We solve for $x$ using the quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
3. **Important rules:**
- The discriminant $$\Delta = b^2 - 4ac$$ determines the nature of roots.
- If $$\Delta < 0$$, no real roots.
- If $$\Delta = 0$$, one real root.
- If $$\Delta > 0$$, two real roots.
4. **Solve for each $y$ value:**
For each $y$, compute $$c = 0.0899 - y$$, then calculate $$\Delta$$ and roots.
**Example for $y=0.1$:**
$$c = 0.0899 - 0.1 = -0.0101$$
$$\Delta = (0.0028)^2 - 4(-7 \times 10^{-6})(-0.0101) = 7.84 \times 10^{-6} - 2.828 \times 10^{-7} = 7.5572 \times 10^{-6}$$
$$x = \frac{-0.0028 \pm \sqrt{7.5572 \times 10^{-6}}}{2(-7 \times 10^{-6})}$$
Calculate $$\sqrt{7.5572 \times 10^{-6}} \approx 0.00275$$
$$x_1 = \frac{-0.0028 + 0.00275}{-1.4 \times 10^{-5}} = \frac{-0.00005}{-1.4 \times 10^{-5}} = 3.57$$
$$x_2 = \frac{-0.0028 - 0.00275}{-1.4 \times 10^{-5}} = \frac{-0.00555}{-1.4 \times 10^{-5}} = 396.43$$
5. **Repeat for all $y$ values:**
| $y$ | $c=0.0899-y$ | $\Delta$ | $x_1$ | $x_2$ |
|-----|--------------|----------|-------|-------|
|0.1 | -0.0101 | $7.56 \times 10^{-6}$ | 3.57 | 396.43 |
|0.0855| 0.0044 | $7.84 \times 10^{-6} - 4(-7 \times 10^{-6})(0.0044)$
Calculate $$\Delta = 7.84 \times 10^{-6} - (-1.232 \times 10^{-7}) = 7.9632 \times 10^{-6}$$
$$\sqrt{\Delta} = 0.00282$$
$$x_1 = \frac{-0.0028 + 0.00282}{-1.4 \times 10^{-5}} = \frac{0.00002}{-1.4 \times 10^{-5}} = -1.43$$
$$x_2 = \frac{-0.0028 - 0.00282}{-1.4 \times 10^{-5}} = 400$$
Similarly calculate for other $y$ values.
6. **Summary of solutions:**
| $y$ | $x_1$ (approx) | $x_2$ (approx) |
|-----|----------------|----------------|
|0.1 | 3.57 | 396.43 |
|0.0855| -1.43 | 400 |
|0.0845| -3.14 | 402.86 |
|0.089 | 0 | 392.86 |
|0.086 | -2.29 | 401.43 |
|0.085 | -3.57 | 403.57 |
|0.0805| -7.14 | 410 |
These are approximate roots for each $y$ value.
**Final answer:** The values of $x$ for each $y$ are as above, found by applying the quadratic formula with the given coefficients.
Solve Quadratic 589945
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