1. **Problem:** Use synthetic division to divide a polynomial by a linear binomial.
2. **Step 1: Identify divisor root.** For division by $x - r$, the root is $r$.
3. **Step 2: Write coefficients.** Write down the coefficients of the dividend polynomial in descending order of powers.
4. **Step 3: Setup synthetic division table.** Place root $r$ to the left and draw a horizontal line for the result.
5. **Step 4: Bring down first coefficient.** Bring the first coefficient down as is.
6. **Step 5: Multiply and add repeatedly.** Multiply the root $r$ by the number just written and add to the next coefficient. Repeat this across all coefficients.
7. **Step 6: Interpret result.** The numbers at the bottom (except last) form the coefficients of the quotient polynomial. The last number is the remainder.
**Example:** Divide $2x^3 - 3x^2 + 4x - 5$ by $x - 2$.
1. Root is $r=2$.
2. Coefficients: $2, -3, 4, -5$.
3. Setup:
| 2 | |
| --- | --- |
| | 2 | -3 | 4 | -5 |
4. Bring down 2.
5. Multiply 2 by 2 = 4, add to -3 = 1.
6. Multiply 2 by 1 = 2, add to 4 = 6.
7. Multiply 2 by 6 = 12, add to -5 = 7.
Bottom row: $2, 1, 6, 7$.
So quotient is $2x^2 + x + 6$ and remainder is 7.
Therefore:
$$\frac{2x^3 - 3x^2 + 4x - 5}{x - 2} = 2x^2 + x + 6 + \frac{7}{x - 2}$$
Synthetic Division
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