Odpowiedź:
[tex]2.d)(3ab - 7)(3 - 7ab) = 9ab - 21 {a}^{2} {b}^{2} - 21 + 49ab = 58ab - 21 {a}^{2} {b}^{2} - 21 \\ [/tex]
[tex]e)( - x + y)(5x + 6y) = - {5x}^{2} - 6xy + 5xy + 6 {y}^{2} = { - 5x}^{2} - xy + {6y}^{2} [/tex]
[tex]f)(x + 5y)(7x - y) = {7x}^{2} - xy + 35xy - {5y}^{2} = {7x}^{2} + 34xy - {5y}^{2} [/tex]
[tex]g)(2x - y)(x + y) = {2x}^{2} + 2xy - xy - {y}^{2} = {2x}^{2} + xy - {y}^{2} [/tex]
[tex]h)(ab - a)(2ab + 6a) = 2 {a}^{2} {b}^{2} + 6 {a}^{2} b - 2 {a}^{2} b - {6a}^{2} = 2 {a}^{2} {b}^{2} + 4 {a}^{2} b - {6a}^{2} [/tex]
