Chapter 3: Problem 10
Use synthetic division to perform the indicated division. Write the polynomial in the form \(p(x)=d(x) q(x)+r(x)\). \(\left(4 x^{2}-5 x+3\right) \div(x+3)\)
Short Answer
Expert verified
Using synthetic division, the division gives \((4x^2 - 5x + 3) = (x + 3)(4x - 17) + 54\).
Step by step solution
01
Identify the Terms
First, recognize the dividend polynomial as \(4x^2 - 5x + 3\) and the divisor as \(x + 3\). We will perform synthetic division using the zero of the divisor, which is \(-3\) in this case.
02
Set Up the Synthetic Division
Create the synthetic division setup. In the top row, write the coefficients of the dividend polynomial: \(4, -5, 3\). The zero of the divisor, \(-3\), is placed to the left.
03
Perform the Synthetic Division
Bring down the leading coefficient \(4\). Multiply \(4\) by \(-3\) and place the result \(-12\) under the next coefficient \(-5\). Add \(-5 + (-12) = -17\) and write \(-17\) below. Continue the process: multiply \(-17\) by \(-3\) to get \(51\), and add \(3 + 51 = 54\).
04
Interpret the Result
The result from synthetic division is \(4x - 17\) with a remainder of \(54\). This means the division can be expressed as: \(p(x) = d(x)q(x) + r(x)\) or \(4x^2 - 5x + 3 = (x + 3)(4x - 17) + 54\).
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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 process similar to the long division method learned in elementary arithmetic, but here, instead of numbers, we use polynomials. It is a way to divide a polynomial by another polynomial, resulting in a quotient and a possible remainder. When performing polynomial division, we essentially try to see how many times the divisor polynomial can "fit" into the dividend polynomial.There are two main forms of polynomial division:
- Long division: A traditional method similar to number division, but this approach can be lengthy and complex with higher degree polynomials.
- Synthetic division: A quicker alternative for division, particularly useful when the divisor is a linear polynomial of the form \(x-c\).
Remainder Theorem
The Remainder Theorem is a useful tool when working with polynomials. It states that when a polynomial \(p(x)\) is divided by a linear divisor \(x - c\), the remainder of this division is equal to \(p(c)\). In simpler terms, if you want to find out the remainder of the division of \(p(x)\) by \(x-c\), you can simply substitute \(c\) into the polynomial.During this exercise:
- The divisor polynomial is \(x + 3\).
- The zero of the divisor is \(-3\).
- By substituting \(-3\) into \(4x^2 - 5x + 3\), the value we obtain is the remainder.
Zero of the Polynomial
The zero of a polynomial is a value for which the polynomial evaluates to zero. It's a key aspect when performing synthetic division. For the divisor \(x + 3\), we set the expression equal to zero and solve for \(x\). Hence, \(x + 3 = 0\) gives us \(x = -3\).Here's why finding the zero is important:
- In synthetic division, instead of using the divisor directly, we use its zero value. This simplifies calculations significantly.
- Zeros help determine polynomial roots and, thus, potential places where the polynomial crosses the x-axis when graphed.
- Knowing the zeros can also aid in factoring polynomials efficiently.
Polynomial Coefficients
The coefficients of a polynomial are the numbers that multiply the variable terms in a polynomial expression. They play a pivotal role during polynomial division as they form the basis of synthetic division.For the given polynomial, coefficients were:
- For \(4x^2\): 4
- For \(-5x\): -5
- For the constant term \(+3\): 3