Question

先化简,在求值(1/2-x+1)/(x-3/x方-4)乘(x/x方+4x+4)其中x=-1

Answer 1

[1/(2-x)+1]/[(x--3)/x^2-4)]*[x/(x^2+4x+4)]

[(3-x)/(2-x)]*[(x-2)(x+2)/(x--3)]*[x/(x+2)^2]

=x/(x+2)

当x=-1时

原式=-1