∵x²>0
∴x-1>0
∴当x>1时,(x-1)/x²的值为正的
当x+1>0时,(x+1)/x²的值为正数
∴x>-1
∴当x>-1时,(x+1)/x²的值为正数
当x+2�ǵġ����԰���һ��ô����(u-2v)/(u+2v)-(8uv)/(u²-4v²)=(u-2v)²/(u+2v)(u-2v)-(8uv)/(u+2v)(u-2v)=[(u-2v)²-8uv]/(u²-4v²)=(u²-4uv+4v²-8uv)/(u²-4v²)=(u²-12uv+4v²)/(u²-4v²)����׷��һ���������ԵĻ��������⣺(2x��-5�η�y��ƽ��)��-3�η�(2x^-5y²)^-3=(2y²/x^5)^-3=(x^5)/(2y²)³=(x^15)/(8y^6)