ce 04 paper 2 q42

This symbol is talking a case "and".
In your question above, this means there are 3 conditions to be satified
i, a /= b
ii, a^2 = 4a + 3
iii, b^2 = 4b + 3

42.
a^2 = 4a + 3 => a = 1 or 3
b^2 = 4b + 3 => b = 1 or 3
as a /= b => [a=1 and b=3] or [a=3 and b=1]
(a+1)(b+1) = ab + a + b + 1
for both case above, we finally have (a+1)(b+1) = 8

2011-12-01 13:15:25 補充：
sorry, my mistake
a and b are roots of quadratic equation x^2 - 4x - 3 = 0
=> sum of root, a+b = 4
=> product of root, ab = -3
(a+1)(b+1) = ab + a + b + 1 = (-3) + (4) + 1 = 2

"{ "這個符號在這裏是"和"的意思.

例如,
{ x + y = 1
{ x - y = -1

即是 x+y = 1 而且 x - y = -1的意思 .