[tex]64 - {m}^{3} {n}^{3} = (4 - mn)(16 + 4mn + {m}^{2} {n}^{2} )[/tex]

[tex] {5x}^{2} - 3x = 0 \\ x(5x - 3) = 0 \\ x = 0 \\ \\ 5x - 3 = 0 \\ 5x = 3 \\ x = 0.6[/tex]

[tex] {25y}^{2} + 30y + 9 = 0 \\ D = {30}^{2} - 4 \times 25 \times 9 = 600 - 900 = - 300 \\ x = ∅[/tex]