Cześć!
[tex]c)(x - y)(3x + 4y) = 3 {x}^{2} + 4xy - 3xy - 4 {y}^{2} = 3 {x}^{2} + xy - 4 {y}^{2} [/tex]
[tex]d)(xy - y)(5xy + 3y) = 5 {x}^{2} {y}^{2} + 3x {y}^{2} - 5x {y}^{2} - 3 {y}^{2} = 5 {x}^{2} {y}^{2} - 2x {y}^{2} - 3 {y}^{2} [/tex]
Pozdrawiam!
