Помогите решить систему    x^3-y^3=98 {   xy^2-yx^2=-30

x^3-y^3=98 xy^2-yx^2=-30 (x-y)(x^2+xy+y^2)=98 xy(y-x)=-30 xy(x-y)=30 x-y=30/xy (30/xy)(x^2+xy+y^2)=98 30(x ^ 2+xy+y ^ 2)=98xy 30x ^2-68xy+30y ^ 2=0       y<>0 30x ^ 2/y ^ 2 - 68xy/y ^ 2+30=0 (x/y)=a 30a ^ 2-68a+30=0 15a ^ 2-34a+15=0 d=34 ^ 2-4*15*15=256=16 ^ 2 a1=5/3 a2=3/5 1) x/y=5/3 x=5y/3 (5y/3) ^ 3-y ^ 3=98 (125y ^ 3-27y ^ 3 )/27=98 98y ^3 /27=98 y ^3/27=1 y ^ 3=27 y=3    =>    x=5 2) x/y=3/5 x=3y/5 (3y/5) ^3-y ^ 3=98 27y ^ 3/125 y ^3=98 (27y ^ 3-125y ^ 3)/125=98 -98y ^ 3/125=98 -y ^ 3/125=1 y ^ 3=-125 y=-5   =>   x= -3