how do you factor -x^2-1

Question

how do you factor -x^2-1

Answer 1

-x² -1

= -1-x²

= i² - x²

= (i + x) (i - x )

Answer 2

a² – b² = (a – b)(a + b)
~~~~~~~~~~~
 –(x² + 1) = (x² – (√(-1))² = – (x – i)(x + i) = (i – x)(x + i) 
                                                   i = √(-1)