(a²+2a-1)-(b^4-2b²-1)=0
a²+2a-1-b^4+2b²+1=0
a²-b^4+2a+2b²=0
(a-b^2)(a+b^2)+2(a+b^2)=0
(a+b^2)(a-b^2+2)=0