Question

分解因式：4a^2-（a^2+1）^2

Answer 1

4a^2-（a^2+1）^2
=(2a+a^2+1)(2a-a^2-1)
=-(a+1)^2(a-1)^2

Answer 2

4a^2-（a^2+1）^2
=4a^2-a^4-2a^2-1
=-(a^4-2a^2+1)
=-(a^2-1)^2
=-(a+1)^2(a-1)^2