直线2x-y-2=0与x,y轴分别相交于A(1,0),B(0,-2)=>AB=√5
设P(x,4x²),d为P到直线2x-y-2=0的距离,
则d=l2x-4x²-2l/√5=2l-2(x-1/4)²+7/8l/√5≤7/4√5
∴S△PAB=AB*d/2≤7/8
此时P(1/4,1/4)