a)2x-3y=7/*(-3) 3x-5y=11/*2 -6x+9y=-21 6x-10y=22 ------------------ -y=1 y=-1 2x-3y=7 y=-1 2x-3(-1)=7 y=-1 2x=7-3 y=-1 x=2 y=-1 b){5p-2r=21/*3 {3p-5p=-3/*(-5) {15p-6r=63 +{-15p+25r=30 _____________ 19r=93/19 r=4,89 5p-2*4,89=21 r = 4,89 5p=21+9,78 r=4,89 5p=30,78/:5 r=4,89 p=6,15 r=4,89 c)2x-3y=10 5x+5y=0 2x-3y=10 5x=-5y :5 2x-3y=10 x=-y 2(-y)-3y=10 x=-y -2y-3y=10 x=-y -5y=10:(-5) x=-y y=-2 x=-y y=-2 x=-(-2) y=-2 x=2 d)4x + 5y = 12,3 /*3 3x - 2y = -4 /*(-4) 12x+15y=36,9 -12x+8y=16 ___________ 23y=52,9 //23 y=2,3 4x + 5y = 12,3 /*2 3x - 2y = -4 /*5 8x+10y=24,6 15x-10y=-20 _____________ 23x= 4,6 / /23 x=0,3 y=2,3 e)3x-0,2y=35 2,5x-5y=5 3x-0,2y=35 2,5x= 5+5y /:2,5 3x-0,2y=35 x= 2 + 2y 3(2+2y) - 0,2y = 35 x= 2 + 2y 6+6y-0,2y=35 x= 2 + 2y 5,8y=29/:5,8 x= 2+2y y=5 x=2+10=12
a)2x-3y=7/ x 3 3x-5y=11/ x (-2) 6x-9y=21 -6x+10y=-22 y=1 b) 5p-2r=21 /x 3 3p+5r= -6 /x(-5) 15p-6r=63 -15p-25r=30 -31r=93 r=93:(-31) r=3 c) 2x-3y=10/ x 5 5x+5y=0 / (-2) 10x-15y=50 -10x-10y=0 -25y=50 y=50:(-25) y=-2 d) 4x+5y=12,3 / x 3 3x-2y=-4 / x (-4) 12x+15y=36,9 -12x+8y=16 23y=52,9 y=52,9:23 y=2,3 e) 3x-0,2y=35 / x (-25) 2,5x-5y=5 -75x+5y=-875 2,5x-5y=5 -72,5x=-870 x=-870:(-72,5) x=12
a) 2x-3y=7/*(-3) 3x-5y=11/*2 -6x+9y=-21 6x-10y=22 -y=1/:(-1) y=-1 2x-3*(-1)=7 2x+3=7/-3 2x=4/:2 x=2 y=-1 b)5p-2r=21/*5 3p+5r=-6/*2 25p-10r=105 6p+10r=-12 31p=93/:31 p=3 5p-2r=21 15-2r=21/-15 -2r=6/:(-2) r=-3 p=3 c)2x-3y=10/*5 5x+5y=0/*3 10x-15y=50 15x+15y=3 25x=53/:25 x=2,12 2x-3y=10 4,24-3y=10/-4,24 -3y=5,76/:-3 y=-1,92
