2、① 6,3/2,3/8,0,3/8,3/2,6;
-6,-2/3,-3/8,0,-3/8,-3/2,-6
② Sketch
3 、( 1)y = 2x? The point (1, 2) is on a parabola.
(2) The opening is upward, the vertex coordinate is (0,0), the symmetry axis is the Y axis, and the parabola is above the X axis.
4. Omission
5、y = - 1/9x?
6 、( 1)y = -3/50x?
(2) Substitute x = 5 into y = -3/50x? , y =-1.5, and the water level reached the warning line after 22.5 hours.