z.17 rozwiaz uklad rownan 6(x-y)+7(x+y)=12 6x-7y=13 z.13 Rozwiaz uklad rownan metoda podstawiania x=y 8x-y=7

x=y 8x-y=7 x=y 8y-y=7 7y=7/:7 y=1 x=1 6(x-y)+7(x+y)=12 6x-7y=13 6x-6y+7x+7y=12 6x-7y=13 13x+y=12/*7 6x-7y=13 91x+7y=84 6x-7y=13 + 97x=97/:97 x=1 6*1-7y=13 -7y=7/:(-7) y=-1

a) 6(x - y) + 7(x + y) = 12 6x - 7y = 13 6x - 6y + 7x + 7y = 12 6x - 7y = 13 13x + y = 12 6x - 7y = 13 y = 12 - 13x 6x - 7(12 - 13x) = 13 y = 12 - 13x 6x - 84 + 91x = 13 y = 12 - 13x 97x = 97      /:97 x = 1  y = 12 - 13 * 1 = 12 - 13 y = -1    {x = 1 {y = -1        b) x = y 8x - y = 7 x = y 8y - y = 7 7y = 7      /:7 y = 1    x = 1 {x = 1 {y = 1