a){x+y=9 {x-y=3 2x = 12 x = 6 6+y=9 y = 3 b){3x+2y=2 {-3x+y=10 3y = 13 y = 4 3x + 8 = 2 x = -2 c){3x+2y=2 / *(-1) {2x+2y=2 -3x - 2y = -2 2x + 2y = 2 -x = 0 0 + 2y = 2 y = 1 d){x+4y=11 / * (-5) {2x+5y=10 / * 4 -5x - 20y = -55 8x + 20y = 40 3x = -15 x = -5 -5 + 4y = 11 y = 4 h){9x+8y=1 / * (-5) {5x-6y=11 / * 9 -45x - 40y = -5 45x - 54y = 99 -99y = 99 y = -1 9x - 8 = 1 x = 1
a) x+y=9 x-y=3 x+y+x-y=9+3 2x=12 //2 x=6 x+y=9 6+y=9 y=3 b) 3x+2y=2 -3x+y=10 3x+2y-3x+y=2+10 3y=12 //3 y=4 3x+2y=2 3x+2*4=2 3x=-6 //3 x= -2 c) 3x+2y=2 2x+2y=2 / (-1) 3x+2y=2 -2x-2y=-2 3x+2y-2x-2y=2-2 x=0 2x+2y=2 2*0+2y=2 2y=2 //2 y=1 d)x+4y=11 /(-2) 2x+5y=10 -2x-8y=-22 2x+5y=10 -2x-8y+2x+5y=-22+10 -3y=-12 /(-3) y=4 x+4y=11 x+4*4=11 x=11-16 x=-5 h) 9x+8y=1 /3 5x-6y=11 /4 27x+24y=3 20x-24y=44 27x+24y+20x-24y=3+44 47x=47 //47 x=1 5x-6y=11 5*1-6y=11 -6y=6 //(-6) y=-1
