=1/(x-5)-6/(x+5)(x-5)-(x+1)/2(x+5)=2(x+5)/2(x+5)(x-5)-12/2(x+5)(x-5)-(x+1)(x-5)/2(x+5)(x-5)=(2x+10-12-x²+4x+5)/2(x²-25）=(-x²+6x+3)/(2x²-50)=-(x²-6x-3)/(2x²-50)