分式的计算题,
能做几题做几题!
1.1/(x^2+3x+2)+1/(x^2+5x+6)+1/(x^2+4x+3)
2.[a/(a-b)-a^2/(a^2-2ab+b^2)]÷[a/(a-b)+a^2/(b^2-a^2)]
3.x+2y/(x^2-y^2-z^2-2yz)-x+2y/(y^2+z^2-x^2+2yz)
4.b/(a-b+c)+2a+c/(b-a-c)+b-c/(b-a-c))