(1) {х-8у-17=0 {3x+4y-23=0 (2) {8x-9y-21=0 {3x-2y-12=0 N1548 (2) {0.3x-0.5y=0 {0.1x+2y=6.5 (4) {0.7x+6y=27.9 {1.5x-2y=-14.5

(1) {х-8у-17=0 {3x+4y-23=0 х=17+8у 3(17+8у)+4y-23=0 51+24у+4у=23 28у=23-51 28у=-28 у=-1 х=17+8*(-1)=17-8=9 (2) {8x-9y-21=0 {3x-2y-12=0 3x-2y-12=0 3х=12+2у х=(12+2у)/3 8(12+2у/3)-9y-21=0 (96+16у-27у)/3=21 96-11у=21*3 11у=96-63 11у=33 у=3 х=(12+2*3)/3=18/3=6 N1548 (2) {0.3x-0.5y=0 {0.1x+2y=6.5 0.1x+2y=6.5 0,1х=6,5-2у х=(6,5-2у)/0,1 х=(6,5-2у)*10 0.3(6,5-2у)*10 -0.5y=0 3(6,5-2у) -0.5y=0 19,5-6у-0,5у=0 6,5у=19,5 у=3 х=10(6,5-2*3)=10*0,5=5 (4) {0.7x+6y=27.9 {1.5x-2y=-14.5 1.5x-2y=-14.5 2у=1,5х+14,5 у=(1,5х+14,5)/2 0.7x+6(1,5х+14,5)/2=27.9 0.7x+3(1,5х+14,5)=27.9 0,7x+4,5х+43,5=27,9 5,2х=27,9-43,5 5,2х=-15,6 х=3 у=(1,5*3+14,5)/2=19/2=9,5