(X+21)/((X+3)(X-3)=X/(X+3) ДОМНОЖАЕМ НА (X-3) X+21=X(X-3) X+21=X^2-3X X+21-X^2+3X=0 X^-4X-21=0 ПО ВИЕТА X1+X2=4 X1*X2=-21 X1=7 X2=-3