Factor the expression and use the fundamental identities to simplify.

1-2 cos^2x + cos^4x

this is just

(1-cos^2)^2 = (sin^2)^2 = sin^4

To factor and simplify the expression 1-2cos^2x+cos^4x using the fundamental identities, we can start by recognizing that cos^4x can be expressed as (cos^2x)^2.

So, the expression becomes 1-2cos^2x + (cos^2x)^2.

Now, let's manipulate the expression using the fundamental identities:

1 - 2cos^2x + (cos^2x)^2
= 1 - 2cos^2x + cos^2x * cos^2x
= 1 - 2cos^2x + (1 - sin^2x) * (1 - sin^2x)
= 1 - 2cos^2x + (1 - 2sin^2x + sin^4x)

Now, let's combine like terms:

= 1 - 2cos^2x + 1 - 2sin^2x + sin^4x
= 2 - 2cos^2x - 2sin^2x + sin^4x

Finally, we can simplify further by using the Pythagorean identity, sin^2x + cos^2x = 1:

= 2 - 2(1 - sin^2x) - 2sin^2x + sin^4x
= 2 - 2 + 2sin^2x - 2sin^2x + sin^4x
= -sin^4x + 2sin^2x

Therefore, the simplified expression is -sin^4x + 2sin^2x.