Chapter 5: Problem 39
Factor expression completely. If an expression is prime, so indicate. \(-17 x^{2}+16+x^{4}\)
Short Answer
Expert verified
The expression factors completely as \((x - 1)(x + 1)(x - 4)(x + 4).\)
Step by step solution
01
Rearrange the Expression
Rearrange the terms to write the polynomial in standard form by ordering the terms by descending powers of x: \[ x^4 - 17x^2 + 16. \]
02
Consider the Quadratic Form
Recognize that the expression \(x^4 - 17x^2 + 16\) can be viewed as a quadratic in terms of \(x^2\). Let \(y = x^2\). Then, the expression becomes:\[ y^2 - 17y + 16. \]
03
Factor the Quadratic Expression
We now factor \(y^2 - 17y + 16\) as we would a quadratic:Find two numbers that multiply to 16 (constant term) and add to -17 (coefficient of the linear term). These numbers are -16 and -1.Thus, we can write:\[ y^2 - 17y + 16 = (y - 16)(y - 1). \]
04
Substitute Back
Since we let \(y = x^2\), substitute back to get the factors in terms of \(x\):\[ (x^2 - 16)(x^2 - 1). \]
05
Apply the Difference of Squares
Factor each of the expressions \(x^2 - 16\) and \(x^2 - 1\) using the difference of squares formula:\[ x^2 - 16 = (x - 4)(x + 4), \]\[ x^2 - 1 = (x - 1)(x + 1). \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The difference of squares is a special pattern in algebra used to factor certain polynomials. This pattern emerges whenever two perfect squares are subtracted. For example, in the expressions \(x^2 - 16\) and \(x^2 - 1\), both terms consist of two perfect squares. You can notice they follow the format of \(a^2 - b^2\).
To factor using the difference of squares:
This method is beneficial because it simplifies complex expressions by transforming them into products of two simpler bi-nomials without losing any terms. Understanding this pattern allows for efficient factorization of more complicated polynomial expressions, enhancing problem-solving skills in algebra.
To factor using the difference of squares:
- Identify the squares: In \(x^2 - 16\), the terms are \(x^2\) and \(4^2\); in \(x^2 - 1\), they are \(x^2\) and \(1^2\).
- Apply the formula: \(a^2 - b^2 = (a - b)(a + b)\).
This method is beneficial because it simplifies complex expressions by transforming them into products of two simpler bi-nomials without losing any terms. Understanding this pattern allows for efficient factorization of more complicated polynomial expressions, enhancing problem-solving skills in algebra.
Quadratic Form
In algebra, viewing complex polynomials as quadratic forms is a useful strategy. A quadratic form is typically expressed as \(ax^2 + bx + c\). Recognizing that a polynomial like \(x^4 - 17x^2 + 16\) can fit this form is crucial. If we set \(y = x^2\), the expression transforms into \(y^2 - 17y + 16\).
This simplification relies on:
This simplification relies on:
- Identifying that the highest power term is a square, in this case, \(x^4 = (x^2)^2\).
- Using the substitution can make the polynomial more manageable for further operations, like factorization.
Polynomial Factorization
Polynomial factorization is a process of decomposing a polynomial into a product of simpler polynomials. It involves identifying patterns and applying algebraic techniques to break down complex expressions. In the provided exercise, the steps of factorization included recognizing a quadratic form and applying the difference of squares.
Steps to factor polynomials:
Steps to factor polynomials:
- Rearrange and simplify: Write in standard form if necessary, as shown when transforming \(-17x^2 + 16 + x^4\) to \(x^4 - 17x^2 + 16\).
- Recognize patterns: Check for special forms like difference of squares or quadratic forms.
- Apply techniques: Factoring out squares or using other identities to simplify the expression.