shen 30天以前 x^2=y,2y=x+3 => 2x^2=x+3 => 2x^2-x-3=0 => x=3/2,-1 (1) x=3/2 y=(3/2)^2=9/4 x+y=15/4 (2) x=-1 y=(-1)^2=1 x+y=0 因此x+y max=15/4 留言