y = -2x^2 + 8x -5
开口向上
=> y = 2x^2 - 8x + 5
并向上,下平移的一新抛物线
y+ n = 2x^2 - 8x + 5
y = 2x^2 - 8x + 5 - n
新抛物线与直线y=kx+1有一个交为（3,4）
4 = 18 - 24 + 5 -n
n = -5
新抛物线
y =2x^2 - 8x + 10 # (1)
(3,4)
直线y=kx+1
4 = 3k+1
k = 1
直线y=x+1 (2)
from (1) and (2)
x+1 = 2x^2 - 8x + 10
2x^2-9x+9 =0
(x-3)(2x-3) = 0
x = 3 or 3/2
x=3/2 ,y = 5/2
另一个交点(3/2,5/2)