13/(x-4)-10/(x-3)=4/(x-5)-1/(x-1)
左右两边分别通分得
（3x+1)/(x-4)(x-3)=(3x+1)/(x-5)(x-1)
∴3x+1=0或(x-4)(x-3)=(x-5)(x-1)
∴x=-1/3或x=7
1/(x+1)+1/(x+7)=1/(x+5)+1/(x+3)
2(x+4)/(x²+8x+7)=2(x+4)/(x²+8x+8)
x+4=0或x²+8x+7=x²+8x+8(无义)
x=-4