(X-1)(X+1)=0所以X-1=0 或者X+1=0所以X=1或者X=-1
(x-1)(x+1)=0推出x-1=0或x+1=0推出x=1或x=-1
(X-1)(X+1)=0(X-1)=0或(X+1)=0所以X=1或X=-1
(X-1)*(X+1)=X2-1 X2=1 X=1或-1
x=1或x=-1
