Chapter 5: Problem 98
Factor each expression. $$ 1-y^{6} $$
Short Answer
Expert verified
The expression factors to \((1-y)(1+y+y^2)(1+y)(1-y+y^2)\).
Step by step solution
01
Recognize the pattern
The expression is of the form 1 minus a perfect square, which is a difference of squares. It can be expressed as \( (1)^2 - (y^3)^2 \).
02
Apply difference of squares formula
The difference of squares formula is \( a^2 - b^2 = (a-b)(a+b) \). For this expression, \( a = 1 \) and \( b = y^3 \).
03
Factor using the formula
Substitute \( a \) and \( b \) into the formula: \[ 1-y^6 = (1-y^3)(1+y^3) \].
04
Factor further using difference of cubes (optional)
The expression \( 1-y^3 \) can be further factored using the difference of cubes formula: \( (1-y^3) = (1-y)(1+y+y^2) \). The expression \( 1+y^3 \) can also be factored using the sum of cubes: \( (1+y^3) = (1+y)(1-y+y^2) \).
05
Write final expression
Combining the factors, the fully factored expression is: \[ (1-y)(1+y+y^2)(1+y)(1-y+y^2) \].
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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 common technique used in algebra to factor expressions. It is based on the identity \( a^2 - b^2 = (a-b)(a+b) \). In simple terms, whenever you have two terms each raised to a power of two, separated by a minus sign, you can factor them using this formula.For instance, consider the expression \( 1 - y^6 \). We can view this as a perfect square problem because we recognize it as \( (1)^2 - (y^3)^2 \). Here:
- \( a = 1 \)
- \( b = y^3 \)
Difference of Cubes
The difference of cubes formula allows us to factor expressions of the form \( a^3 - b^3 \). The formula used is \( a^3 - b^3 = (a-b)(a^2 + ab + b^2) \). Understanding this pattern aids in breaking down more complex cubic expressions into simpler, manageable parts.Digging into our specific example, when factoring \( 1 - y^6 \), we initially get \( 1-y^3 \) from the difference of squares. Applying the difference of cubes formula, with:
- \( a = 1 \)
- \( b = y \)
Sum of Cubes
The sum of cubes is closely related to the difference of cubes. The formula to factor these types of expressions is \( a^3 + b^3 = (a+b)(a^2 - ab + b^2) \). Like its counterpart, the sum of cubes helps turn complex cubic expressions into a product of simpler binomials and trinomials.Returning to our example, after applying the difference of squares, we address \( 1 + y^3 \). Using the sum of cubes formula where:
- \( a = 1 \)
- \( b = y \)