(1)(a^3-4ab^2)/(a^3-4a^2b+4ab^2)
=a(a^2-4b^2)/a(a^2-4ab+4b^2)
=[a(a-2b)(a+2b)]/a(a-2b)^2
=(a+2b)/(a-2b)
=[-2+2*(-0.5)]/[-2-2*(-0.5)]
=(-2-1)/(-2+1)
=3
(2)(1-4x^4)/(2x^3+x)
=(1-2x^2)(1+2x^2)/x(2x^2+1)
=(1-2x^2)/x
(3)(x^2y-2xy+y)/(y-x^2y)
=y(x^2-2x+1)/y(1-x^2)
=y(x-1)^2/y(1-x)(1+x)
=-(x-1)/(1+x)
=(1-x)(1+x)