Let X be a random variable, e (x) = 2, e (x ^ 2) = 6, then d (x) is equal to?

Let X be a random variable, e (x) = 2, e (x ^ 2) = 6, then d (x) is equal to?

Because D (x) = e (x Λ 2) - (E (x)) Λ2
So D (x) = 6-2 Λ 2 = 2
2 Λ 2 is the square of 2

The known set a = {x ︱ X5}, B = {x ︱ A is less than or equal to X

A is really contained in B
No, it should be a, it really contains B
Then a ≤ x < A + 4 is in the range of X5
A ≤ x < A + 4 is in the range of X5
Then a > 5
So a ≤ - 5, a > 5

Given a = {x ︱ X4}, B = {x ︱ 2a is less than or equal to x, less than or equal to a + 3}, if B is contained in a,
Find the value range of real number a,

Given a = {x ︱ X & lt; - 1 or X & gt; 4}, B = {x ︱ 2a is less than or equal to X and less than or equal to a + 3}, if B is contained in a,
B = empty set
2a>a+3
a>3
a+3<-1
a<-4
2a>4
a>2
therefore
The value range of a is a & lt; - 4 or a & gt; 2