因式分解x(y+2)-x-y-1
x(y+2)-x-y-1=(x-1)(y+1)
因式分解:x^2(y^2-1)+(1-y^2)
^2表示二次方
原式=x^2(y^2-1)-(y^2-1)
=(y^2-1)(x^2-1)
=(y+1)(y-1)(x+1)(x-1)
-99加100减97加98减95加96.减1加2等於多少
50