1/2x-6(x-1/3Y²)+(-3/2x+Y²)
=1/2x-6x＋2Y²-3/2x+Y²
=1/2x-6x-3/2x＋2Y²+Y²
=-7x＋3Y²
∵X=-8/3,Y=-1/3
∴原式=﹣7x＋3Y²=﹣7x﹙﹣8/3﹚+3﹙-1/3﹚²
=56/3+1/3
=19