1.y-3/4y^2-8 除以 （ 5/y-2 -y-2)
题目好像有问题?
2.化简求值 ：（ x^2+2/x^2-4x+4 - x+1/x-2) 除以 x+4/2-x
其中 X= 7/4 .
=[(x^2+2)/(x-2)^2-(x+1)/(x-2)]*(2-x)/(x+4)
=[x^2+2-(x+1)(x-2)]/(x-2)^2*[-(x-2)]/(x+4)
=-(x^2+2-x^2+x+2)/(x-2)*1/(x+4)
=-(x+4)/(x-2)*1/(x+4)
=-1/(x-2)
=-1/(7/4-2)
=-1/(-1/4)
=4