х1^2 * x2^4 + x2^2 * x1^4=(х1^2 * x2^2)*(x2^2+x1^2)=
=(x1*x2)^2((x1+x2)^2-2x1*x2)=((-5)^2)*[(-1)^2-2*(-5)]=
=25*(1+10)=25*11=275
