0.0625a^4－b^4
=(0.25a)^4-b^4
=[(0.25a)^2+b^2][(0.25a)^2-b^2]
=[(0.25a)^2+b^2](0.25+b)(0.25-b)
-1+s^4
=s^4-1
=(s^2+1)(s^2-1)
=(s^2+1)(s+1)(s-1)