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Use long division to divide. \(\left(x^{3}-9\right) \div\left(x^{2}+1\right)\)

Short Answer

Expert verified
The quotient is \(x\) and the remainder is \(-x-9\). Thus the division result can be written in the form \(x - \frac{x+9}{x^2+1}\).

Step by step solution

01

Set Up the Problem

Write the division problem in long division format. Write \(x^{3}-9\) under the long division symbol and \(x^{2}+1\) to the left of the symbol.
02

Divide and Write the Answer in Quotient

Divide the first term in the dividend \(x^{3}\) by the first term in the divisor \(x^{2}\) to get \(x\). Write \(x\) above the long division line, at the top.
03

Multiply and Subtract

Multiply the divisor \(x^{2}+1\) by the quotient \(x\) obtained in Step 2, and subtract the product from the dividend \(x^{3}-9\). The result is \((-x-9)\).
04

Continue the Process

Divide the new term \(-x\) by the first term in the divisor \(x^{2}\). We find that \(x^{2}\) cannot go into \(-x\), so \(-x\) becomes our remainder. Thus, the solution is \(x\) with a remainder of \(-x-9\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Polynomial Long Division
Polynomial long division is a method used in algebra for dividing one polynomial, which is called the dividend, by another, which is the divisor. The process is similar to long division with numbers and involves a sequence of divide, multiply, subtract, and bring down steps. Just as with numerical long division, the goal is to determine how many times the divisor can 'fit' into the dividend.

Here's what the process looks like in a general sense:
  • First, arrange both polynomials in descending order of their degrees.
  • Divide the first term of the dividend by the first term of the divisor to get the first term of the quotient.
  • Multiply the entire divisor by this term and subtract the result from the dividend.
  • Bring down the next term from the dividend, if there is one.
  • Repeat these steps until you reach a remainder that has a degree less than that of the divisor or is zero.

The remainder, if it exists, is expressed as a fraction over the divisor. Throughout this process, keep in mind that like terms should be aligned vertically for clarity. One of the most important aspects when working on polynomial long division is to ensure that all powers of the variable are accounted for. If a term is missing, place a zero term in its standard position (e.g., if there is an \(x^{3}\) term but no \(x^{2}\) term, write \(0 \times x^{2}\)).
Dividing Polynomials
Dividing polynomials can at first seem intimidating, but understanding the reasoning behind each step can make the process much clearer. The division of polynomials helps simplify expressions and is a useful tool in finding roots of a polynomial function. The key steps in dividing polynomials are:
  • Identifying the highest degree terms in both the dividend and divisor.
  • Seeking to eliminate the highest degree term of the dividend in a stepwise manner.
  • Accounting for any 'gaps' in degrees by introducing terms with zero coefficients.
  • Continuing the process till the degree of the remainder is less than the degree of the divisor or until the remainder is zero.

The result of the division is presented as a quotient plus a remainder over the divisor, if a remainder exists. This is akin to writing the result of a numerical division as a mixed number.
Algebraic Long Division
Algebraic long division, while sharing the same fundamental steps with numerical long division, deals with the division of algebraic expressions. The core goal here is to rewrite a complex polynomial as a simpler polynomial plus a remainder. Understanding how to align and subtract polynomials is critical in this process.

Key considerations include:
  • Being meticulous with signs; a common mistake is to wrongly subtract polynomials during the process.
  • Understanding that the degree (the highest exponent of the variable in any term) of the remainder must always be less than the degree of the divisor.
  • Knowing that if the degree of a term in the remainder is equal to or larger than the divisor, further division steps are required.

For instructional clarity, providing worked examples with different types of polynomials can greatly aid in understanding. Challenges often arise when dealing with missing terms or complex polynomials, so practice with a variety of exercises is recommended to gain proficiency.

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