(3) Let y=0, and you can get X 2-4x-3 = 0. If you solve x=2, you can add and subtract the root number 7, then ab=2 times the root number 7. Because the vertex coordinates are (-2a-b, 4a-4ac-b squared) and the vertex coordinates are (2, -7), the height of this triangle is 7, so the area is 7 times.

(4) y = 61x 2.

(5) If the time is X, bp=8-2x, bq=x, the area is S=-x square +4x, and the formula is -(x-2) square +4, so the maximum value is 4 and the exercise time is 2s.