将x+5分解为x-1+6，则原式=∫(x-1)/(x^2-2x-1)dx+∫6/(x^2-2x-1)dx=∫1/2(x^2-2x-1)d(x^2-2x-1)+3/根号2乘以×∫1/((x-1)^2-2)dx=1/2ln(x^2-2x-1)+3/根号2ln(x-1-跟号2）/x-1+根号2）+C
