1、B
2、1,-2,-1;3,0,5;
-½,3,0;2,2, - 4;
3、y = -2/3x² + 7/3x + 1
4、(1)S = -½x² + 4x(0 < x < 8)
(2)7/2,8,6
5、(1)如y = x² + 2x等
(2)如y = x² + 2x - 2等
6、(1)y =(80 + 2x)(50 + 2x)- 4x² + 260x + 4000
(2)由题意得4x² + 260x + 4000 = 10800,解得x1 = -85(舍去),x2 = 20。所以金色纸边的宽为20 cm
*7、y = x² + 2x - 1