rozwiąż układ równań dwoma metodami a.18x-21y=2 24x-15y=7

a. Metoda przeciwnych współczynników 18x-21y=2 / * - 12 24x-15y=7 / * 9 - 216x + 252 y = -24 216 x -135 y = 63 ....................dodajemy stronami 117y = 39 /117 y = 39/117 = 1/3 Podstawiamy y do równania 18x-21y=2 18x - 21 * 1/3 = 2 18x - 7 = 2 18x = 2 + 7 18x = 9 /:18 x = 9/18 = 1/2 Metoda podstawiania 18x-21y=2 24x-15y=7 18x = 2 + 21y / :18 24x-15y=7 x = 1/9 + 21/18y 24 * (1/9 + 21/18y) - 15y = 7 x = 1/9 + 21/18y 24/9 + 28y - 15y = 7 x = 1/9 + 21/18y 13y = 7 - 2 i 2/3 x = 1/9 + 21/18y 13y = 4 i 1/3 x = 1/9 + 21/18y 13y = 13/3 /:13 x = 1/9 + 21/18y y = 13/3 * 1/13 x = 1/9 + 21/18y y = 1/3 x = 1/9 + 21/18 * 1/3 y = 1/3 x = 2/18 + 7/18 y = 1/3 x = 9/18 = 1/2 y = 1/3