Odpowiedź:
zad. 1
1.
[tex] - 7x + zy = - 7x + 2 \times ( - 9) = - 7x - 18[/tex]
[tex](3x + 5y)(8 - y) = 24x - 3xy + 40y - 5 {y}^{2} = 24 \times 3 - 3 \times 3 \times ( - 2) + 40 \times ( - 2) - 5 \times {( - 2)}^{2} = 72 + 18 - 80 - 5 \times 4 = 72 + 18 - 80 - 20 = - 10[/tex]