Adriano's answer is correct. Explanation: See solution.
Practice makes perfect
Let's factor the expression to check if either answer is correct. We can begin by factoring out any common factors using the Distributive Property.
x^8-x^4 ⇒ x^4(x^4-1)Since, we only have two terms within the parentheses, we can check for a difference of squares.
x^4( x^4-1)
⇕
x^4( x^2+1)( x^2-1)
Then, because the first term of each factor in parentheses can still be squared, we will check for a difference of squares again.
x^4(x^2+1)( x^2-1)
⇕
x^4(x^2+1)( x-1)( x+1)
We cannot factor out any other terms. Therefore, Adriano correctly factored the expression.