9(x-7y)-(5y-2x)+20y dla x=0,5 , y=0,3 (5x+7y)-8(y+1)+3(x-y) dla x=½ , u=¼

9(x-7y)-(5y-2x)+20y= 9x-63y-5y+2x+20y=11x-48y 11×0,5-48×0,3=5,5-14,4=-8,9 (5x+7y)-8(y+1)+3(x-y)= 5x+7y-8y-8+3x-3y= 8x-4y-8 8×0,5-4×0,25-8=4-1-8=-5 ½=0,5 ¼=0,25

9x-63y-5y+2x+20y=11x-48y 11*0,5=5,5 48*0,3=14,4 5,5-14,4=-8,9 5x+7y-8y-8+3x-3y=8x-4y-8 8*0,5=4 4*14=1 4-1-8=-11