Question

先化简再求值先化简再求值：（x-x/x+1）(x+1/x^2+4x+4)(x^2-4/x^2-2x),其中x=-0.5

Answer 1

[x-x/(x+1)][(x+1)/(x^2+4x+4)][(x^2-4)/(x^2-2x)]

=[x^2/(x+1)][(x+1)/(x+2)^2][(x+2)(x-2)/x(x-2)]

=x/(x+2)

当x=-0.5时

原式=-0.5/（-0.5+2）=-1/3