Known samples x1, X2 If the variance of XN is 5, then samples 3x1 + 2, 3x2 + 2 What is the variance of 3XN + 2?

Known samples x1, X2 If the variance of XN is 5, then samples 3x1 + 2, 3x2 + 2 What is the variance of 3XN + 2?

Using the formula: D (AX + b) = a ^ 2DX;
D(X1,X2,…… ,Xn)=5；
Then d (3x1 + 2,3x2 + 2,...) ,3Xn+2)=9D(X1,X2,…… ,Xn)=45

(1 + Half) x (1-half) x (1 + Third) x (1-third) x... X (1 + 99th) x (1-99th) =?

(1 + Half) x (1-half) x (1 + Third) x (1-third) x... X (1 + 99th) x (1-99th) put together = (1 + 1 / 2) (1 + 1 / 3) (1 + 1 / 4) (1+1/99) ×(1-1/2)(1-1/3)(1-1/4)…… (1-1/99)=3/2×4/3×5/3…… 100/...

Half and one third
(1 / 2 plus 1 / 3... Plus 1 / 2010) plus (1 / 2 plus 1 / 3... Plus 1 / 2009) minus (1 / 2 plus 1 / 3... Plus 1 / 2010) plus (1 / 2 plus 1 / 3... Plus 1 / 2009)
(1/2 + 1/3 +......1/2010)*(1+ 1/2+ 1/3+......1/2009)-(1+ 1/2 + 1/3+......1/2010)*( 1/2 +1/3 +......1/2009)

Five sixths

Half and one third, etc

1/2+1/3=3/6+2/6=5/6

How much is half and one third

1 / 2 + 1 / 3 = 3 / 6 + 2 / 6 = 5 / 6 (5 / 6)
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What is the meaning of English letter combination?

For example, every letter in English has its original meaning. No matter how it evolves, to a certain extent, it retains the meaning of trace and alphabetic meaning. For example, ST is a fixed meaning. There should be a large number of other alphabetic combinations

Explain the meaning of the following sets
A={x|y=x^2+2x-1,x∈R}
B={y|y=x^2+2x-1,x∈R}
C={(x,y)|y=x^2+2x-1,x∈R}
D={s|s=t^2+2x-1,t∈R}

A
The element is X
Here x belongs to R
So a is r
B
The element is y
y=(x+1)²-2≥-2
So B is a set of real numbers greater than or equal to - 2
C
The element is (x, y)
That's the point
So it's a point in the image of a quadratic function
D
The element is s
s=(t+1)²-2≥-2
So he's the same as B

How does family explain and what does each letter mean

family=father and mother i love you

How to explain the meaning of set sum
A={x|y=x^2+2x-1,x∈R}
B={y|y=x^2+2x-1,x∈R}
C={(x,y)|y=x^2+2x-1,x∈R}
D={s|s=t^2+2x-1,t∈R}

A represents the value range of X in y = x ^ 2 + 2x-1, and the title tells you that it is x ∈ R, so a is R. B represents the value range of Y in y = x ^ 2 + 2x-1, that is, the value range of x ^ 2 + 2x-1. C represents the point pair of y = x ^ 2 + 2x-1, that is, C is actually the function image, So we only need to treat x as known, and the resulting D is an expression about X

What four character idiom has the meaning of "annotation, explanation"

According to the classics and its notes, it means that there is a basis for speaking. It means that the old official document is used to end the above which shows the reason and explains the reason. It is used to cause the following which is the center of gravity. It refers to routine business and bureaucratic articles