(x²+1)/[(x+1)²(x-1)]=A/(x+1)+B/(x+1)²+C/(x-1)=[(A+C)x²+(B-2C)x+(-A+B+C)]/[(x+1)²(x-1)]A+C=1B-2C=0-A+B+C=1A=1/4B=1/2C=1/4
