x^2/(x-1)^2+x^2/(x+1)^2=40/9x^2(2x^2+2)/[(x-1)^2(x+1)^2]=40/99x^2(x^2+1)=20(x^2-1)^29x^4+9x^2=20x^4-40x^2+2011x^4-49x^2+20=0 x1=2 x2=-2 x3=√55/11x4=-√55/11