(2) there is no intersection with the x axis, and delta = (2b) 2-4c < 0, that is, b 2 < c.

There are 6×6=36 situations when the dice are rolled twice, including (1, 2) (1, 3) (1, 4) (1, 5) (1, 6) (2 ?.

(3)ξ=0, 1,2

P (zeta = 0) = 7/36 (from question (2))

△ = (2b) 2-4c = 0, and b 2 = c, there are cases of (2,4).

P(ξ= 1)= 1/36

△ = (2b) 2-4c > 0, b 2 > c, there are 36- 1-7=28 cases,

P(ξ=2)=28/36

e(ξ)= 7/36×0+ 1/36× 1+28/36×2 = 57/36

Hope to adopt ~