a ) 2x+y=5 /*1 2x-3y= 11 -2x-y=-5 2x-3y = 11 -2y=6 / (-2) y=-3 b) 2x+ 7y=16 / *(-2) 4x + 3y =10 -4x -14y= -32 4x-3y=10 -17y=22 /:17 y= 22/7 (/kreska ułamkowa ) y=3 1/7 c) x+2y =-3 / * (-2) 2x-y=-1 -2x-4y =6 2x-y= -1 5y=4 /:5 y = 4/5 (/ kreska ułamkowa )
a) 2x+y=5 2x-3y=11 y=5-2x 2x-3*(5-2x)=11 y=5-2x 2x-15+6x=11 y=5-2x 2x+6x=11+15 y=5-2x 8x=26 y=5-2x x=3,25 y=5-2*3,25 x=3,25 y= -1,5 x=3,25 b) 2x+7y=16 4x+3y=10 x+3,5y=8 4x+3y=10 x=8-3,5y 4(8-3,5y)=10 x=8-3,5y 32-14y=10 x=8-3,5y -14y=10-32 x=8-3,5y -14y= -22 x=8-3,5y y=1,57 x=8-3,5*1,57 y=1,57 x=8-5,50 y=1,57 x=2,50 y=1,57 c) x+2y=-3 2x-y=-1/*2 X+2Y= -3 4X-2y= -2 --------------- 5x= -5 x= -1 2x-y=-1 2*(-1) -y = -1 -2-y= -1 -y= -1+2 -y=1 y = -1
