Zadanie Rozwiąż układy równań: a) x+3y=0 y-x=4 b) x-5y= -2 2x+y= -4 c) x-3y=0 x+y= -4 d) x+y = -4 2x-3y= 2
źródło:
a) x+3y=0 y-x=4 --------- x = -3y podstawiam: y-(-3y)=4
y+3y=4
4y=4 |:4 y = 1 x = -3y x=-3*1 x = -3
b) x-5y= -2 2x+y= -4 ------- x=5y-2 2(5y-2)+y=-4
10y-4+y=-4 |+4 11y=0 y = 0 x=5y-2 x=5*0-2 x = -2
c) x-3y=0 x+y= -4 --------- x=3y
3y+y=-4
4y=-4 |:4 y = -1 x=3y x=3*(-1) x = -3
d) x+y = -4 2x-3y= 2 -------- y=-x-4 2x-3(-x-4)=2 2x+3x+12=2 |-12 5x=-10 |:5 x = -2 y=-x-4
y=-4-(-2)
y=-4+2 y = -2