b+1/c=1得b=1-1/c c+1/a=1得c=1-1/a (ab+1)/b =a+1/b =a+1/(1-1/c) =a+c/(c-1) =a+(1-1/a)/[(1-1/a)-1] =a+[(a-1)/a]/(-1/a) =a+[-(a-1)] =1y= x2+2x+1/x2-1 除 x+1/x2-x -x+1=(x+1)^2/[(x+1)(x-1)]*x(x-1)/(x+1) -x...