Chapter 6: Problem 11
Use synthetic division to divide. $$ \left(2 x^{3}-x^{2}-7 x+14\right) \div(x+2) $$
Short Answer
Expert verified
The quotient is \(2x^2 - 5x + 3\) with a remainder of 8.
Step by step solution
01
- Set Up Synthetic Division
First, identify the coefficients of the polynomial. For the polynomial given, the coefficients are: 2 (for \(2x^3\)), -1 (for \(-x^2\)), -7 (for \(-7x\)), and 14 (constant term). Also, identify the zero of the divisor \(x + 2\), which is -2.
02
- Write the Coefficients
Write the coefficients in a row: 2, -1, -7, 14. Place the zero of the divisor (which is -2) to the left side.
03
- Begin Synthetic Division
Bring down the first coefficient (2) directly below the line.
04
- Multiply and Add
Multiply -2 (zero of the divisor) by the number you just brought down (2), and write the result under the next coefficient: -2 * 2 = -4. Add this result to the next coefficient (-1): -1 + (-4) = -5.
05
- Repeat Process
Repeat the process: Multiply -2 by -5 to get 10, and add this to the next coefficient (-7): -7 + 10 = 3. Then, multiply -2 by 3 to get -6, and add this to the next coefficient (14): 14 + (-6) = 8.
06
- Write the Quotient and Remainder
The bottom row now reads 2, -5, 3, 8. These numbers represent the coefficients of the quotient polynomial and the remainder. The quotient polynomial is \(2x^2 - 5x + 3\) and the remainder is 8.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
polynomial division
Polynomial division is a method used to divide a polynomial by another polynomial of lower degree. It's similar to long division with numbers, but we work with polynomial expressions instead. In our example, we are dividing \((2x^3 - x^2 - 7x + 14)\) by \( (x + 2)\). There are different methods for polynomial division, including long division and synthetic division.
- Long Division: It involves writing out divisions and remainders, just like traditional long division.
- Synthetic Division: This is quicker and simpler for dividing polynomials when the divisor is a linear polynomial (in the form \(x - a\)).
quotient and remainder
When dividing polynomials, the result consists of a quotient and a remainder. The quotient is the polynomial that you get from the division, and the remainder is what's left over. In our example:
- The quotient polynomial is found by using synthetic division which gives us \((2x^2 - 5x + 3)\).
- The remainder is the value that doesn’t nicely divide by the divisor, which in this case is 8.
- It helps us rewrite the original division in the form \( \text{Dividend} = \text{Divisor} \times \text{Quotient} + \text{Remainder} \).
- This form provides a way to verify the result of the division.
coefficients in algebra
Coefficients are the numerical parts of the terms in a polynomial. In the polynomial \(2x^3 - x^2 - 7x +14 \):
- 2 is the coefficient of \(x^3\)
- -1 is the coefficient of \(-x^2 \)
- -7 is the coefficient of \(-7x \)
- 14 is a constant term (also a coefficient).
- The coefficients are [2, -1, -7, 14]
- The zero of the divisor \((x+2)\) is -2
- Bringing down the first coefficient directly.
- Multiplying the zero of the divisor by each successive value brought down.
- Adding the result to the next coefficient in the polynomial.