Chapter 5: Problem 96
Factor. Assume that variables used as exponents represent positive integers. $$ x^{4 n}-625 $$
Short Answer
Expert verified
The expression factors into \((x^n - 5)(x^n + 5)(x^{2n} + 25)\).
Step by step solution
01
Identify the Structure of the Expression
The given expression is \(x^{4n} - 625\). This is a difference of squares structure because \(625\) is a perfect square, and can be written as \(25^2\).
02
Apply the Difference of Squares Formula
The formula for the difference of squares is \(a^2 - b^2 = (a - b)(a + b)\). In this case, take \(a = x^{2n}\) and \(b = 25\).
03
Factor Using the Formula
Substitute \(a\) and \(b\) into the difference of squares formula to factor the expression: \(x^{4n} - 625 = (x^{2n} - 25)(x^{2n} + 25)\).
04
Identify Potential Further Factoring
Check each factor to see if they can be factored further. Notice that \(x^{2n} - 25\) is another difference of squares because \(25\) is \(5^2\).
05
Factor Again Using the Difference of Squares
Apply the difference of squares formula again to \(x^{2n} - 25\): \(x^{2n} - 25 = (x^n - 5)(x^n + 5)\).
06
Present the Fully Factored Form
Combine all the factored terms: \(x^{4n} - 625 = (x^n - 5)(x^n + 5)(x^{2n} + 25)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
When you come across expressions like \(x^{4n} - 625\), you might notice that it fits a special pattern known as the "difference of squares." This pattern is characterized by the structure \(a^2 - b^2\), where both \(a\) and \(b\) are squared terms. In our example:
However, the story doesn't end there. The expression \(x^{2n} - 25\) is itself a difference of squares, allowing for further factoring.
- The first term \(x^{4n}\) can be seen as \(a^2\) when rewritten as \( (x^{2n})^2\).
- The second term \(625\) is actually \(25^2\).
However, the story doesn't end there. The expression \(x^{2n} - 25\) is itself a difference of squares, allowing for further factoring.
Exponents
Exponents can initially seem a little tricky, but they're important for simplifying and factoring expressions like \(x^{4n} - 625\). They indicate how many times a number, termed the base, is multiplied by itself. Let's delve further into the example given:
- \(x^{4n}\) means \(x\) is multiplied by itself \(4n\) times. Think of \(4n \) simply as a number counting the multiplications.
- Similarly, in the intermediate step, \(x^{2n}\) indicates that \(x\) is multiplied by itself \(2n\) times.
- When you square an expression like \(x^{2n}\), you multiply the exponent by 2, resulting in \(x^{4n}\).
- Learning how expressions break down or get simplified due to exponents is key for smooth problem-solving.
Perfect Squares
A perfect square is a number that can be expressed as the square of an integer. Recognizing perfect squares in expressions is a helpful skill in factoring.In our example, \(625\) is a perfect square because it equals \(25^2\). This recognition allows the difference of squares strategy to be employed.
- To determine if a number is a perfect square, simply check if its square root results in a clean integer. For \(625\), its square root is \(25\), which confirms it's a perfect square.
- Another perfect square noticed earlier in factoring was \(x^{2n}\), which makes \(x^{4n}\) as the square of \(x^{2n}\).