Final answer:
To factor the expression a⁴ - b⁴ completely, we can use the difference of squares formula.
Step-by-step explanation:
To factor the expression a⁴ - b⁴, we can use the difference of squares formula. This formula states that a² - b² can be factored as (a + b)(a - b). Applying this formula to the expression a⁴ - b⁴, we get (a² + b²)(a² - b²). However, we can factor a² - b² further as (a + b)(a - b). Therefore, the completely factored form of a⁴ - b⁴ is (a² + b²)(a + b)(a - b).