How do you factor #x^4-8x^2+16#?
Make a dumby variable, in this case I will use
This is equivalent to
You can now plug in
Now, you can factor this like a normal polynomial.
Finally, you plug in
The factored form will be
Notice how this is almost a simple quadratic trinomial. In fact, it can be thought of as a quadratic of
We can easily factor this quadratic.