How do you factor x^(4n) - y^(4n)x4ny4n?

1 Answer
May 12, 2016

(x^(2n)+y^(2n))(x^n+y^n)(x^n-y^n)(x2n+y2n)(xn+yn)(xnyn)

Explanation:

Note that both x^(4n)x4n and y^(4n)y4n are squared terms:

  • x^(4n)=(x^(2n))^2x4n=(x2n)2
  • y^(4n)=(y^(2n))^2y4n=(y2n)2

With this knowledge, we will factor this expression as a difference of squares:

  • color(red)a^2-color(blue)b^2=(color(red)a+color(blue)b)(color(red)a-color(blue)b)a2b2=(a+b)(ab)

Thus, we see that

x^(4n)-y^(4n)x4ny4n

=(color(red)(x^(2n)))^2-(color(blue)(y^(2n)))^2=(x2n)2(y2n)2

=(color(red)(x^(2n))+color(blue)(y^(2n)))(color(red)(x^(2n))-color(blue)(y^(2n)))=(x2n+y2n)(x2ny2n)

Notice that we can factor (x^(2n)-y^(2n))(x2ny2n) in the same way:

x^(4n)-y^(4n)=(x^(2n)+y^(2n))(x^(2n)-y^(2n))x4ny4n=(x2n+y2n)(x2ny2n)

=(x^(2n)+y^(2n))((x^n)^2-(y^n)^2)=(x2n+y2n)((xn)2(yn)2)

=(x^(2n)+y^(2n))(x^n+y^n)(x^n-y^n)=(x2n+y2n)(xn+yn)(xnyn)