x^2(x^2-1)+4(1-x^2) =x^2(x^2-1) - 4(x^2-1)
提取公因式=(x^2-1)(x^2-4)
平方差公式=(x+1)(x-1)(x+2)(x-2)
(50又1/11)^2 - (49又10/11)^2
平方差公式=[(50又1/11)+(49又10/11)]*[(50又1/11)-(49又10/11)]
=100*(2/11)
=200/11