把X= 4/3代入2X-1/2=1/2X+▲得:
2*(4/3) -1/2 = (1/2) *(4/3) +▲
即:8/3 -1/2= 2/3 +▲
故:▲= 8/3 -1/2 -2/3= 2 -1/2= 3/2