a) 2x-3y=7 /*3 3x-5y=11 /*(-2) 6x-9y=21 -6x+10y=-22 y=-1 2x-3*(-1)=7 2x+3=7 2x=7-3 2x=4 /:2 x=2 b) 5p-2r=21 /*5 3p+5r=-6 /*2 25p-10r=105 6p+10r=-12 31p=93 /:31 p=3 3*3+5r=-6 9+5r=-6 5r=-6-9 5r=-15 /:5 r=-3 c) 2x-3y=10 /*(-5) 5x+5y=0 /*2 -10x+15y=-50 10x+10y=0 25y=-50 /:25 y=-2 5x+5*(-2)=0 5x+(-10)=0 5x=10 /:5 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+5*2,3=12,3 4x+11,5=12,3 4x=12,3-11,5 4x=0,8 /:4 x=0,2 e)ten przyklad mi nie wychodzi:( sory
a. {2x - 3y = 7/ *5 3x - 5y = 11/*(-3) {10x - 15y=35 -9x + 15y=-33 + x= 2 2*2 - 3y=7 -3y=7-4 -3y=3/:(-3) y=-1 b. { 5p 2r=21/*5 3p+5r=6/*2 {25p - 10r = 125 6p + 10r = 12 31p=137/:31 p=4,4 5*4,4 - 2r=21 22-2r=21 22-21=2r 1-2r/:2 r=1 c. {2x-3y=10/*5 5x+5y=0 {10x - 15y=50 -10x - 10y=0 -25y=50/(-25) y= -2 2x -3*2=10 2x - 6=10 2x=4/:2 x=2 d. {4x +5y=12,3/*2 3x-2y=-4/*5 {8x +10y = 24,6 15x - 10y= -20 23x= 4.4/:23 x= 0.2 4*0.2 + 5y= 12.3 0.8 +5y=12.3 5y= 11.5/:5 y=2.3 e. { 3x- 0.2y = 33/(-25) 2.5x - 5y=5 { -75 +5y = -825 2.5x - 5y=5 -72.5x= -825 / : (-72.5) x= 11.3 2.5 * 11.3 - 5y=5 28.25 - 5y=5 23.25=5y/:5 y=4.65
