2a+1－a+3a2－4a－5÷a2－9a2－3a－10.解原式=[x+2x(x－2)－x－1(x－2)2]x4－x(括号内分式的分母中的多项式式分解因式.分式的除法法则)=[(x+2)(x－2)x(x－2)2－x(x－1)x(x－2)2]x4－x(异分母的分式减法的法则)=x2－4－x2+xx(x－2)2x4－x(整式运算)=x－4x(x－2)2x4－x(合并同类项)=x－4x(x－2)2（－xx－4）(分式的符号法则)=－1(x－2)2.(分式的乘法法则)计算x+yx2－xy+（x2－y2x）2（1y－x）3.解原式=x+yx(x－y)+(x+y)2(x－y)2x21(y－x)3=x+yx(x－y)－(x+y)2x2(x－y)=x2+xy－x2－2xy－y2x2(x－y)=－xy－y2x2(x－y)=－xy+y2x2(x－y).x－y+4xyx－y）（x+y－4xyx+y）答案x2－y2[1(a+b)2－1(a－b)2]÷（1a+b－1a－b）答案2a(a+b)(a－b);xx－yy2x+y－x4yx4－y4÷x2x2+y2答案－xyx+y3x－2x2－x－2+（1－1x+1）÷（1+1x－1）答案x2(x+1)(x－2);（2xx+1+2x－1+4xx2－1）×（2xx+1+2x－1－4xx2－1）.答案4(2m^2-4m)/(2-m)(m-1)-(1+m)/(1-m^2)=2m(m-2)/(2-m)(m-1)-(1+m)/(1-m)(1+m)=-2m/(m-1)-1/(1-m)=(2m-1)/(1-m)(-1)-a^2)/(a-1)-a=(1-a-a^2-a^2+a)/(a-1)=-(2a^2-1)/(a-1)（5/x-1）-（3/x+2）+（3/x+3）-（5/x-2）原式=[5(x+2)-3(x-1)]/(x-1)(x+2)-[5(x+3)-3(x-2)]/(x-2)(x+3)=(2x+13)/(x+x-2)-(2x+21)/(x+x-6)=[(2x+13)(x+x-6)-(2x+21)(x+x-2)]/(x+x-6)(x+x-2)=(2x+16x+x-78-2x-23x-17x+42)/(x+x-6)(x+x-2)=(-7x-16x-36)/(x^4+2x-7x-8x+12)就这些了.追问不够,再来一些就给你分回答(1）1/6x-4y-1/6x+4y+3x/4y^2-9x^2=[6x+4y-(6x-4y)-12x]/(36x^2-16y^2)=(8y-12x)/(36x^2-16y^2)=4(2y-3x)/[4(3x+2y)(3x-2y)]=-1/(3x+2y)(2)1/1-x+1/1+x+2/1+x^2+4/1+x^4=2/(1-x^2)+2/(1+x^2)+4/(1+x^4)=4/(1-x^4)+4/(1+x^4)=8/(1-x^8)1.（2x分之3）+2=02.（x-1分之x）+（x+1分之2）=13.（x+1分之1）-（x+3x+2分之x）=-13/2x=-23=-4xx=-3/4x/(x-1)+2/(x+1)=1x(x+1)+2(x-1)=(x-1)(x+1)x^2+x+2x-2=x^2-13x=1x=1/31/(x+1)-x^2/(x^2+3x+2)=-11/(x+1)-x^2/(x+1)(x+2)=-1(x+2)/(x+1)(x+2)-x^2(x+1)(x+2)=-1x+2-x^2=-(x+1)(x+2)x^2-x-2=x^2+3x+24x=-4x=-1拓展：原题=1-1/2+1/2-1/3.+1/99-1/100=1-1/100(2):根据(1)得:1-1/2+1/2-1/3+.+1/N-1/(N+1)=1-1/(N+1)3.(1)1/1*2+1/2*3+1/3*4+...+1/99*100=（1-1/2)+(1/2-1/3）+（1/3-1/4)+...+(1/99-1/100)=1-1/100=99/100(2)1/1*2+1/2*3+1/3*4+...+1/n(n+1)==（1-1/2)+(1/2-1/3）+（1/3-1/4)+...+[1/n-1/(n+1)]=1-1/(n+1)=n/(n+1)