Rozwiąż układy równań metodą podstawienia. a) x+3y=3 x-y=5 b) 3m+n=9 2m-5n=-11 c) 5x=4-2y 4x+y=3

a) x+3y=3 x-y=5 x+3y=3 x=5+y 5+y+3y=3 x=5+y 4y=3-5 x=5+y 4y=-2 x=5+y y=-½ x=5+(-½) y=-½ x=4½ ------------------- b) 3m+n=9 2m-5n=-11 n=9-3m 2m-5(9-3m)=-11 n=9-3m 2m-45+15m=-11 n=9-3m 17m=-11+45 n=9-3m 17m=34 n=9-3m m=2 n=9-3*2 m=2 n=3 m=2 ------------------ c) 5x=4-2y 4x+y=3 5x=4-2y y=3-4x 5x=4-2(3-4x) y=3-4x 5x=4-6+8x y=3-4x 5x-8x=-2 y=3-4x -3x=-2 y=3-4x x=2/3 y=3-4*2/3 x=2/3 y=1/3

a x+3y=3 x-y=5 x = 3 - 3y 3 - 3y - y = 5 3 - 4y = 5 - 4y = 5 - 3 - 4y = 2 y = - 2/4 = - 1/2 x - y = 5 x + 1/2 = 5 x = 5 - 1/2 = 4 i 1/2 b 3m+n=9 2m-5n=-11 n = 9 - 3m 2m - 5(9 - 3m) = - 11 2m - 45 + 15m = - 11 17m = - 11 + 45 2m = 34 m = 17 3m + n = 9 3 razy 17 + n = 9 51 + n = 9 n = 9 - 51 = - 42 c 5x=4-2y 4x+y=3 y = 3 - 4x 5x = 4 - 2(3 - 4x) 5x = 4 - 6 + 8x 5x - 8x = - 2 - 3x = - 2 x = 2/3 4x + y = 3 4 razy 2/3 + y = 3 8 + 3y = 9 3y = 9 - 8 3y = 1 y = 1/3

a). x+3y=3 x-y=5 x+3y=3 x=5+y 5+y+3y=3 x=5+y 4y=3-5 x=5+y 4y=-2 x=5+y y=-0,5 x=5+0,5 x=5,5 y=-0,5 b). 3m+n=9 2m-5n=-11 n=9-3m 2m-5(9-3m)=-11 n=9-3m 2m-45+15m=-11 n=9-3m 17m=34 n=9-3m m=2 n=9-3*2 m=2 m=2 n=4 c). 5x=4-2y 4x+y=3 5x=4-2y y=3-4x 5x+2(3-4x)=4 y=3-4x 5x+6-8x=4 y=3-4x -3x=-2 y=3-4x x=3/2 y=3-4(3/2) x=3/2 y=3-6 x=3/2 y=-3