How to factor this expression

Question

x⁴ -2x²+1

Answer 1

How to factor this expression
x⁴ -2x²+1

(x² - 1)(x²-1)= (x²-1)² This is called a perfect square of the form

 

(a-b)² = a²-2ab+b²   where a = x² , and b = 1

Answer 2

x⁴-2x²+1 is a perfect square

(x²-1)(x²-1)

(x-1)(x+1)(x-1)(x+1)

(x-1)²(x+1)² if you want to write it this way