Chapter 3: Problem 22
Find each quotient when \(P(x)\) is divided by the binomial following it. $$P(x)=x^{4}+4 x^{3}+2 x^{2}+9 x+4 ; \quad x+4$$
Short Answer
Expert verified
The quotient is \(x^3 + 2x + 1\).
Step by step solution
01
Set up the Division
To find the quotient of the polynomial \(P(x) = x^4 + 4x^3 + 2x^2 + 9x + 4\) when divided by \(x+4\), we will use polynomial long division. Set up \(x+4\) as the divisor and \(x^4 + 4x^3 + 2x^2 + 9x + 4\) as the dividend.
02
Divide the Leading Terms
Divide the first term of the dividend, \(x^4\), by the first term of the divisor, \(x\). This gives \(x^3\). Write \(x^3\) as the first term of the quotient above the division symbol.
03
Multiply and Subtract
Multiply \(x^3\) by \(x+4\) to get \(x^4 + 4x^3\). Subtract this from the original polynomial to find the new dividend: \((x^4 + 4x^3 + 2x^2 + 9x + 4) - (x^4 + 4x^3)\) results in \(2x^2 + 9x + 4\).
04
Repeat the Process
Divide the first term of the new dividend, \(2x^2\), by \(x\) to get \(2x\). Multiply \(2x\) by \(x+4\) to get \(2x^2 + 8x\). Subtract \(2x^2 + 8x\) from \(2x^2 + 9x + 4\), leading to \(x + 4\).
05
Continue Division
Divide \(x\) by \(x\) to get \(1\). Multiply \(1\) by \(x+4\), giving \(x + 4\). Subtract \(x + 4\) from \(x + 4\), resulting in \(0\) for the remainder.
06
Write the Final Quotient
The quotient from the division of \(P(x)\) by \(x+4\) has thus been determined to be \(x^3 + 2x + 1\) as the remainder is zero.
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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 one polynomial by another, much like long division with numbers. It's a systematic procedure allowing us to simplify expressions and determine when a polynomial is divisible by another.
- Setup: Write the dividend (the polynomial you're dividing) and the divisor (the polynomial you're dividing by).
- Dividing: Start with the leading terms. Divide the first term of the dividend by the first term of the divisor.
- Multiply and Subtract: Multiply the result by the entire divisor, subtracting it from the dividend to form a new, smaller polynomial. Repeat as needed.
Remainder Theorem
The Remainder Theorem provides a quick way to evaluate the remainder of a polynomial division without performing the entire division. If a polynomial \(f(x)\) is divided by a binomial \((x-c)\), the remainder is simply \(f(c)\).
- This means substituting the constant \(c\) into the polynomial.
- If \(f(c)=0\), then \((x-c)\) is a factor of the polynomial.
Synthetic Division
Synthetic division is a simplified method of dividing a polynomial by a binomial of the form \((x-c)\). It's quicker and less cumbersome than polynomial long division. This technique is effective for polynomials with leading coefficients of 1.
- Setup: List the coefficients of the polynomial in descending order of degree.
- Bring Down the First Coefficient: Write this directly across in the result row.
- Multiply and Add: Multiply the coefficient by \(c\) (from \(x-c\)) and add to the next coefficient. Continue this process through the coefficients.
Factoring Polynomials
Factoring polynomials involves rewriting them as a product of simpler polynomials, which can reveal the roots of the polynomial or simplify the expression for further calculation.
- Identify Common Factors: Factor out the greatest common factor from all terms.
- Factor by Grouping: Combine terms to form groups that can be factored separately.
- Special Forms: Recognize patterns like difference of squares, perfect square trinomials, and sum/difference of cubes.