a) ∑ x+3y=3 ∑ x-y=5 x=3-3y 3-3y-y=5 x=3-3y -4y=2 x=3-3y y=-1/2 x=3-3*(-1/2)=3+1,5=4,5 b) ∑ 2x-y=10 ∑ x+5y= -17 2x-y=10 x=-17-5y 2(-17-5y)-y=10 x=-17-5y -34-10y-y=10 x=-17-5y -11y=44 x=-17-5y y=-4 x=-17-5*(-4)=-17+20=3 c) ∑3m+n=10 ∑2m-5n= -11 n=10-3m 2m-5n=-11 n=10-3m 2m-5(10-3m)=-11 n=10-3m 2m-50+15m=-11 n=10-3m 17m=39 n=10-3m m=39/17 n=10-3*39/17=53/17 d) ∑ 4a-2=b ∑ 3a+7b= 1,5 4a-2=b 3a+7(4a-2)=1,5 b=4a-2 3a+28a-14=1,5 b=4a-2 31a=15,5 b=4a-2 a=0,5 b=4*0,5-2=2-2=0
1] x+3y=3 x-y=5 x+3y=3 x=5+y 5+y+3y=3 4y=3-5 4y=-2 y=-2:4 y=-½ x=5+(-½)=4½ spr, 4½+3×(-½)=3 4½-1½=3 3=3 2] 2x-y=10 x+5y=-17 y=2x-10 x+5(2x-10)=-17 x+10x-50=-17 11x=-17+50 11x=33 x=33:11 x=3 y=2×3-10=6-10=-4 spr. 3+5×(-4)=-17 320=-17 -17=-17 3] 3m+n=10 2m-5n=-11 n=10-3m 2m-5(10-3m)=-11 2m-50+15m=-11 17m=-11+50 17m=39 m=2⁵/₁₇ n=10-3×2⁵/₁₇ n=10-6¹⁵/₁₇ n=3²/₁₇ spr. 2׳⁹/₁₇-5 razy⁵³/₁₇=-11 -11=-11 4] 4a-2=b 3a+7b=1,5 3a+7(4a-2)=1,5 3a+28a-14=1,5 31a=1,5+14 31a=15,5 a=15,5:31 a=0,5 b=4×0,5-2=0 spr. 3×0,5+0=1,5 1,5=1,5
a) x+3y=3 x-y=5 x = 3 - 3y 3 - 3y - y = 5 x = 3 - 3y -4y = 2 /:(-4) x = 3 - 3y y = - 1/2 x = 3 - 3* (-1/2) y = -1/2 x = 3 + 3/2 y = -1/2 x = 4,5 y = -0,5 b) 2x-y=10 x+5y= -17 y = 2x - 10 x + 5*(2x - 10) = -17 y = 2x - 10 x + 10x - 50 = -17 y = 2x - 10 11x = 33 /:11 y = 2x - 10 x = 3 y = 2* 3 - 10 x = 3 y = -4 x = 3 c) 3m+n=10 2m-5n= -11 n = 10 - 3m 2m - 5 * (10 - 3m) = -11 n = 10 - 3m 2m - 50 + 15m = -11 n = 10 - 3m 17m = 39 /: 17 n = 10 - 3m m = 39/17 n = 10 - 3m m = 2 i 5/17 n = 10 - 3* 39/17 m = 2 i 5/17 n = 170/17 - 117/17 m = 2 i 5/17 n = 53/17 m = 2 i 5/17 n = 3 i 2/17 m = 2 i 5/17 d) 4a-2=b 3a+7b= 1,5 b = 4a - 2 3a + 7*(4a - 2) = 1,5 b = 4a - 2 3a + 28a - 14 = 1,5 b = 4a - 2 31a = 15,5 /: 31 b = 4a - 2 a = 0,5 b = 4* 0,5 - 2 a = 0,5 b = 2 -2 a = 0,5 b = 0 a = 0,5
