Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
4. Polynomial Functions
Zeros of Polynomial Functions
Problem 18
Textbook Question
Use the factor theorem and synthetic division to determine whether the second polynomial is a factor of the first. See Example 1. 2x^3+x+2; x+1

1
Identify the divisor from the second polynomial, which is \(x + 1\). According to the factor theorem, if \(x + 1\) is a factor of the first polynomial, then substituting \(-1\) into the first polynomial should yield zero.
Set up synthetic division using \(-1\) as the divisor. Write down the coefficients of the first polynomial \(2x^3 + 0x^2 + x + 2\), which are \([2, 0, 1, 2]\).
Bring down the leading coefficient \(2\) to the bottom row.
Multiply \(-1\) by the number just written on the bottom row (\(2\)) and write the result under the next coefficient (\(0\)). Add this result to the coefficient above it and write the sum below.
Repeat the multiplication and addition process for the remaining coefficients. If the final number on the bottom row (the remainder) is zero, then \(x + 1\) is a factor of the polynomial.
Recommended similar problem, with video answer:

This video solution was recommended by our tutors as helpful for the problem above
Video duration:
4mPlay a video:
Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Factor Theorem
The Factor Theorem states that a polynomial f(x) has a factor (x - c) if and only if f(c) = 0. This theorem is essential for determining whether a given polynomial is a factor of another polynomial. In this context, we will evaluate the first polynomial at the root of the second polynomial, which is -1, to check if it equals zero.
Recommended video:
Guided course
Factor by Grouping
Synthetic Division
Synthetic division is a simplified form of polynomial long division that allows for the division of a polynomial by a linear factor of the form (x - c). It is a more efficient method for performing polynomial division, especially when determining factors. In this case, we will use synthetic division to divide the first polynomial by (x + 1) to see if the remainder is zero, confirming that (x + 1) is a factor.
Recommended video:
Higher Powers of i
Polynomial Remainder Theorem
The Polynomial Remainder Theorem states that when a polynomial f(x) is divided by a linear divisor (x - c), the remainder of this division is f(c). This theorem is crucial for understanding the results of synthetic division. If the remainder is zero, it indicates that the divisor is indeed a factor of the polynomial, which is the goal of the problem at hand.
Recommended video:
Guided course
Introduction to Polynomials
Related Videos
Related Practice