4/5x+x/(5x-25)=5/(x^2-5x)(4x-20)/5x(x-5)+x^2/5x(x-5)=25/5x(x-5)4x-20+x^2=254x+x^2=45x^2+4x+2^2=45(x+2)^2=45+2^2x+2=正负根号49x=-9或5因为x/(5x-25)中,当x=5时,5x-25=0（分母不能为0）所以x=5不符合题意,舍去...