Question

已知二次函数y=2x的平方+bx+c的图像经过(2,3),且顶点在直线y=3x

Answer 1

y = 2x^2 + bx + c = 3x

2x^2 + (b-3)x + c = 0

(b-3)^2 -8c = 0 （一个交点）

b^2 - 6b + 9 - 8c = 0

c = (b-3)^2/8

2*2^2 +b2 + c = 3

c = -2b - 5 = (b-3)^2/8

无解