Here's your answer down here↓:
Explanation:
x^3 - y^3 = (x - y)(x^2 + xy + y^2)
(x^4 - y^4) = (x^2 - y^2)(x^2 + y^2) = (x - y)(x + y)(x^2 + y^2)
Ok. So the factor (x-y) appears once in the top line and once in the second line. So we are going to take it the least amount of times.
So, the factor (x + y) appears in the top line zero times and in the second line one time so we will take it where it appears the least which is zero times so we are still at (x - y)
And it Same goes for the factors of (x^2 + y^2) and (x^2 + xy + y^2)