a)3x+2y=13 2x+y=11*(-2) 3x+2y=13 -4x-2y=-22 -x=-9 x=9 y=-7 b)5x+3y=0 -x-2y=7*5 5x+3y=0 -5x-10y=35 -7y=35/(-7) y=-5 x=3 c)3u+2v=2*(-2) 5u+4v=6 -6u-4v=-4 5u+4v=6 -u=2 u=-2 v=4 d)3s+5t=-6 1,5s-2t=-3*(-2) 3s+5t=-6 -3s+4t=6 9t=0 t=0 s=-2 e)5=3x-y 5x-2y=7 3x-y=5(*-2) 5x-2y=5 -6x+2y=-10 5x-2y=5 -x=-5 x=5 y=10 f)x-3y=5 y+3x=-5*3 x-3y=5 3y+9x=-15 10x=-10 x=-1 y=-2
a) {3x+2y=13 {2x+y=11 |*(-2) {3x+2y=13 +{-4x-2y=-22 ============ -x=-9 x=9 3*9+2y=13 2y=-14 y=-14/2 {x=9 {y=-14/2 b) {5x+3y=0 {-x-2y=7 |*5 {5x+3y=0 {-5x-10y=35 =========== -7y=35 y=-5 5x+3*(-5)=0 5x=15 {x=3 {y=-5 c) {3u+2v=2 |*(-2) {5u+4v=6 {-6u-4v=-4 {5u+4v=6 ========== -u=2 u=-2 5*(-2)+4v=6 4v=16 {v=4 {u=-2 d) {3s+5t=-6 {1,5s-2t=-3 |*(-2) {3s+5t=-6 {-3s+4t=6 ========= 9t=0 t=0 3s+5*0=-6 3s=-6 {s=-2 {t=0 e) {3x-y=5 |*(-2) {5x-2y=7 {-6x+2y=-10 {5x-2y=7 =========== -x=-3 x=3 5*3-2y=7 -2y=-8 {y=4 {x=3 f) {x-3y=5 {3x+y=-5 |*3 {x-3y=5 {9x+3y=-15 ============ 10x=-10 x=-1 -1-3y=5 -3y=6 {y=-2 {x=-1
