：（│x-2│-3）/（x^2-2x-15）=0
∴│x-2│-3=0 x-2=±3 x=5或x=-1
x^2-2x-15≠0 (x-5)(x+3)≠0 x≠5且x≠-3
∴取x=-1
（x-1）/（x+4）=(-1-1)/(-1+4)=-2/3