hi, I need help with this problem

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

Correct me if I am wrong, your equation is:

\frac{(2sin^2(x)-1)^2}{sin^4(x) - cos^4(x)} = 1-2cos^2(x)

There are several identities to keep in mind and it falls into place.

Note that

2sin^{2}(x)-1=-cos(2x)

and

sin^{4}(x)-cos^{4}(x)=1-2cos^{2}(x)

That last one is the same as on the right side of the equation, huh? :)

Thanks...

Um... did you really understood the last two posts! :confused:

not really? =/

If what you asked is really what we understood, then the question you asked is not a good proof.

.. may I ask?. ahm, can u solve, x cube plus x squared minus 7x+5 divided by x+3?. can u get it?.