Rozwiąż metodą podstawiania poniższe układy równań: a) 1/2x + 1/4y = 4 2/3x + 1/2y = 2 b) 2x + 4y = -7 4x - 3y = 8 c) y = 2x - 1 3(x+2) = 5(y-2)

1/2x + 1/4y = 4 /: 1/2 2/3x + 1/2y = 2 /:2/3 x+1/2y=2 x+3/4y=3 x=2-1/2y x+3/4y=3 ---- 2-1/2y+3/4y=3 -1/2y+3/4y=1 1/4y=1 y=4 x+3/4*4=3 x=0 b) 2x + 4y = -7 4x - 3y = 8 c) y = 2x - 1 3(x+2) = 5(y-2)

1/2x-1/4y=4|*2 2/3x+1/2y=2 x-1/2y=8=> x=8+1/2y 2/3(8+1/2y)+1/2y=2 16/3+2/6y+1/2y=2 2/6y+3/6y=2-5 1/3 5/6y=-3 1/3|:5/6 y=-10/3*6/5 y=-4 x=8+1/2y x=8-2 x=6 b)2x+4y=-7|:2 4x-3y=8 x=-7/2-2y 4(-7/2-2y)-3y=8 -14-8y-3y=8 -11y=22 y=-2 x=-3,5-2*(-2) x=0,5 c)y=2x-1 3(x+2)=5(y-2) 3x+6=5(2x-1-2) 3x+6=10x-15 -7x=-21 x=3 y=2x-1 y=5