[tex](x + 5y)(7x - y) = 7 {x}^{2} - xy + 35xy - 5 {y}^{2} = 7 {x}^{2} + 34xy - 5 {y}^{2} [/tex]
[tex](2x - y)(x + y) = 2 {x}^{2} + 2xy - xy - {y}^{2} = 2 {x}^{2} + xy - {y}^{2} [/tex]
[tex](ab - a)(2ab + 6a) = 2 {a}^{2} {b}^{2} + 6 {a}^{2} b - 2 {a}^{2} b + 6 {a}^{2} = 2 {a}^{2} {b}^{2} + 4 {a}^{2} b + 6 {a}^{2} [/tex]
Pozdrowionka! ~Wika
