Автор - rodnikovkadir
Ответ:
1.1)
(0.5x + 4y)(0.5x - 4y) = \ = (0.5x)^{2} - (4y)^{2} = \ = 0.25 {x}^{2} - 16 {y}^{2}
2.1)
(0.9 {m}^{3} + 7 {n}^{3} )(0.9 {m}^{3} - 7 {n}^{3} ) = \ = (0.9 {m}^{3} )^{2} - (7 {n}^{3})^{2} = \ = 0.81 {m}^{6} - 49 {n}^{6}
2.2)
(7m + 0.8)(7m - 0.8) = \ = (7m)^{2} - {0.8}^{2} = \ = 49 {m}^{2} - 0.64
Объяснение: