Question

已知a,b,c,d成等差数列,且曲线y=x^2-2x+3的顶点时（b，c），则a+d等于

A.3
B.2
C.1
D.-2
请写出详细过程

Answer 1

y = x^2 - 2x + 3 = (x-1)^2 + 2,
b = 1, c = 2.
c - b = 1,
a = b-1 = 1-1=0,
d = c+1 = 2+1=3,
a+d = 3.
A.