How do you factor a^4 - 8a^3 + 16^2a48a3+162?

1 Answer
Jun 15, 2017

Assuming you mean a^4 - 8a^3 + 16a^2a48a3+16a2, note the a^2a2 in common:

a^2(a^2 - 8a + 16)a2(a28a+16)

Then, we look for factors of 1616 that when added together in a certain way give 88. As it turns out, this is a perfect square.

= color(blue)(a^2(a - 4)^2)=a2(a4)2

If you multiply this out using the "FOIL" method, you should get the same thing back that you started with:

a^2(a - 4)^2 = a^2(a^2 - 4a - 4a + 16)a2(a4)2=a2(a24a4a+16)

= a^2(a^2 - 8a + 16)=a2(a28a+16)

= a^4 - 8a^3 + 16a^2=a48a3+16a2