[tex](k - m)(k + m) = {k}^{2} - {m}^{2} [/tex]

[tex](3y+5y)(3-5y) = 9y - 15 {y}^{2} + 15y - 25 {y}^{2} = - 40 {y}^{2} + 24 {y} = 24 {y}^{2} - 40y[/tex]

[tex]( \frac{1}{2} m²-n³)( \frac{1}{2} m²+n³) = \frac{1}{4} m ^{4} - n^{9} [/tex]

[tex]m²-n² = (m - n)(m + n)[/tex]

[tex] {c}^{2} - 81 = (c - 9)(c + 9)[/tex]

[tex]0,64x⁶-9y⁸ = (0,8x^{3} - 3 {y}^{4} )(0,8x^{3} + 3 {y}^{4} )[/tex]

[tex](x-1)(x+1)-(x-3)x=2 \\ x ^{2} - 1 - {x}^{2} + 3x = 2 \\ 3x = 3 \\ x = 1[/tex]

[tex]x²-25=0 \\ (x - 5)(x + 5) = 0 \\ x_1 = 5 \\ x_2= - 5[/tex]