Question

根据下列条件求关于X的二次函数的解析式 1.图像经过(0,1) (1,0) (3,0)

Answer 1

1.y = ax^2 + bx+c ,带入(1,-2),(0,3),(-1,-6)解得

y = -7x^2 + 2x + 3

2.y = a(x-3)^2 + b

b = 5

a(1-3)^2 + 5 = 11,a = 3/2

y = 3/2 (x-3)^2 +5

3.y = a(x-1+sqrt(2))(x-1-sqrt(2)) = a((x-1)^2 - 2) = a(x^2 - 2x - 1)

x = 0,y = -2

a = 2

y = 2(x^2-2x-1)

打字不易,