A) {3x+y= -5/*(-3) {2x+3y=6 {-9x-3y=15 {2x+3y=6 ------------ -7x=21/:(-7) x=-3 2*(-3)+3y=6 3y=6+6 3y=12/:3 y=4 B) {3x-2y=8,5/*3 {3y-2x=-9/*2 {9x-6y=25,5 {-4x+6y=-18 --------------- 5x=7,5/:5 x=1,5 -4*1,5+6y=-18 6y=-18+6/:6 y=-2 C) {2(x+2y)-5=-7 {6y-5x+1=6 {2x+4y=-7+5 {6y-5x=6-1 {2x+4y=-2/*5 {-5x+5y=5/*2 {10x+20y=-10 {-10x+10y=10 --------------- 30y=0 y=0 10x+20*0=-10 10x=-10/:10 x=-1 D) {-3(2+y)=6x-30 {2y-5(x+y)=-9 {-6-3y=6x-30 {2y-5x-5y=-9 {-3y-6x=-30+6 {-3y-5x=-9 {-3y-6x=-24 {-3y-5x=-9/*(-1) {-3y-6x=-24 {3y+5x=9 -------------- -x=--15/:(-1) x=15 3y+5*15=9 3y=9-75 3y=-66/:3 y=-22 E) {2(2y-x)=3y+x+8 {-5(x+y)=-4x-y+7 {4y-2x=3y+x+8 {-5x-5y=-4x-y+7 {4y-2x-3y-x=8 {-5x-5y+4x+y=7 {y-3x=8 {-x-4y=7/*(-3) {y-3x=8 {12y+3x=-21 ---------------- 13y=-13/:13 y=-1 -1-3x=8 -3x=8+1 -3x=9/:(-3) x=-3 F) {2(x+y)+3=3(x+2y)-7 -(x+2y)=6y+2x-10 {2x+2y+3=3x+6y-7 {-x-2y=6y+2x-10 {2x+2y-3x-6y=-7-3 {-x-2y-6y-2x=-10 {-x-4y=-10/*(-2) {-3x-8y=10 {2x+8y=20 {-3x-8y=10 -------------- -x=30/:(-1) x=30 2*30+8y=20 8y=20-60 8y=-40/:8 y=-5
Rozumiem, że to są układy równań... Zrobię to metodą podstawiania. więc: a) 3x+y= -5 |*(-3) 2x+3y=6 -9x-3y=15 2x+3y=6 -7x=21 |/(-7) x=-3 x=-3 2x+3y=6 x=-3 -6+3y=6 x=-3 3y=0 x=-3 y=0 b) 3x-2y=8,5 |*2 3y-2x=-9 |*3 6x-4y=17 -6x+9y=-27 5y=10 |/5 y=2 y=2 3y-2x=-9 y=2 6-2x=-9 y=2 -2x=-15 y=-2 x=7 i1/2 c) 2(x+2y)-5=-7 6y-5x+1=6 2x+4y=-2 |*3 6y-5x=5 |*(-2) 6x+12y=-6 10x-12y=-10 16x=-16 x=-1 x=-1 2x+4y=-2 x=-1 4y=-4 x=-1 y=-1 d) -3(2+y)=6x-30 2y-5(x+y)=-9 -6-3y=6x-30 2y-5x-5y=-9 -3y-6x=-24 |*(-1) -3y-5x=-9 3y+6x=24 -3y-5x=-9 x=15 x=15 -3y-5x=-9 x=15 -3y=66 |/(-3) x=15 y=-22 e) 2(2y-x)=3y+x+8 -5(x+y)=-4x-y+7 4y-2x=3y+x+8 -5x-5y=-4x-y+7 y-3x=8 -4y-x=7 |*(-3) y-3x=8 12y+3x=-21 13y=13 y=1 y=1 y-3x=8 y=1 -3x=7 y=1 x=-2 i1/3 f) 2(x+y)+3=3(x+2y)-7 -(x+2y)=6y+2x-10 2x+2y+3=3x+6y-7 -x-2y=6y+2x-10 -x-4y=-10 |*(-3) -3x-8y=-10 3x+12y=30 -3x-8y=-10 20y=20 y=1 y=1 -3x-8y=-10 y=1 -3x=-2 y=1 x=2/3
