Нужно преобразовать : 7,218^3+30*7,218*2,782+2,782^3

7,218+2,782 = 10
сумма кубов: 7,218^3+2,782^3 =
= (7,218+2,782)*(7,218^2-7,218*2,782+2,782^2) 
тогда: 7,218^3+30*7,218*2,782+2,782^3 = 
 =10*7,218^2+20*7,218*2,782+10*2,782^2 =
= 10*(7,218^2+2*7,218*2,782+12,782^2) = 10*(7,218+2,782)² =
= 10*10² = 1000