Pre-calculus factoring help.?

Question

Please help by explaining how to get the answer to these problems. Thank you!

x^4-4x^2+3

x^2-x-3/4

Answer 1

Let x^2=a, so x^4=a^2

We have: a^2-4a+3=(a-1)(a-3)

That means we have (x^2-1)(x^2-3)

The second one cannot be factored.

I just took Alg.

Answer 2

i dont know how to get the first one, but for the second one, you can either use the quadratic formula, or you can complete the square.

the answer would be x=3/2, -1/2