Factor completely: c^4 - 1

(c^2 - 1)(c^2 + 1)

(c - 1)(c + 1)(c^2 + 1)

To factor the expression c^4 - 1 completely, we can start by looking for any patterns or identities that can help us simplify the expression.

In this case, we can notice that the given expression is a difference of squares. The difference of squares identity states that a^2 - b^2 can be factored as (a - b)(a + b).

Applying this identity to the given expression, we can rewrite it as (c^2)^2 - 1^2.

Now we have a^2 - b^2 form, where a = c^2 and b = 1. Using the difference of squares identity, the expression can be factored as:

(c^2 - 1)(c^2 + 1)

The factors are now (c^2 - 1) and (c^2 + 1). However, we can still factor the first factor (c^2 - 1) further, as it is also a difference of squares.

Again, applying the difference of squares identity, we have:

(c - 1)(c + 1)(c^2 + 1)

So, the completely factored form of c^4 - 1 is (c - 1)(c + 1)(c^2 + 1).