[中四數]Functions and Graph[20分]

7. f(k + 1) = k

(k + 1)2 - 2(k + 1) - 5 = k

k2 + 2k + 1 - 2k - 2 - 5 = k

k2 - k - 6 = 0

(k - 3)(k + 2) = 0

k = -2 or 3


2.62. a. The direction of opening of the graph is upward.

b. Put x = 0

y-intercept, y = 7

c. y = x2 - 4x + 7

y = (x - 2)2 + 3

So, the vertex is (2 , 3) and the axis of symmetry is x = 2