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3 years ago

I'm confused on how to simplify variable expressions...

Mathematics

2 answers:

Vitek1552 [10]3 years ago

4 0

Answer:

the answer is 3p

Step-by-step explanation:

gulaghasi [49]3 years ago

3 0

Basically, simplifying variables is the same as regular equations (like 5-3=2 and 5x-3x=2x)

So 7x-x is the same as 7x-1x which equals 6x

And -3p+6p is the same thing as -3+6 but with a p. With this in mind, the answer is 3p

Hope this helps

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Let X and Y be discrete random variables. Let E[X] and var[X] be the expected value and variance, respectively, of a random vari

Ulleksa [173]

Answer:

(a) $E[X+Y]=E[X]+E[Y]$

(b) $Var(X+Y)=Var(X)+Var(Y)$

Step-by-step explanation:

Let X and Y be discrete random variables and E(X) and Var(X) are the Expected Values and Variance of X respectively.

(a)We want to show that E[X + Y ] = E[X] + E[Y ].

When we have two random variables instead of one, we consider their joint distribution function.

For a function f(X,Y) of discrete variables X and Y, we can define

$E[f(X,Y)]=\sum_{x,y}f(x,y)\cdot P(X=x, Y=y).$

Since f(X,Y)=X+Y

$E[X+Y]=\sum_{x,y}(x+y)P(X=x,Y=y)\\=\sum_{x,y}xP(X=x,Y=y)+\sum_{x,y}yP(X=x,Y=y).$

Let us look at the first of these sums.

$\sum_{x,y}xP(X=x,Y=y)\\=\sum_{x}x\sum_{y}P(X=x,Y=y)\\\text{Taking Marginal distribution of x}\\=\sum_{x}xP(X=x)=E[X].$

Similarly,

$\sum_{x,y}yP(X=x,Y=y)\\=\sum_{y}y\sum_{x}P(X=x,Y=y)\\\text{Taking Marginal distribution of y}\\=\sum_{y}yP(Y=y)=E[Y].$

Combining these two gives the formula:

$\sum_{x,y}xP(X=x,Y=y)+\sum_{x,y}yP(X=x,Y=y) =E(X)+E(Y)$

Therefore:

$E[X+Y]=E[X]+E[Y] \text{ as required.}$

(b)We want to show that if X and Y are independent random variables, then:

$Var(X+Y)=Var(X)+Var(Y)$

By definition of Variance, we have that:

$Var(X+Y)=E(X+Y-E[X+Y]^2)$

$=E[(X-\mu_X +Y- \mu_Y)^2]\\=E[(X-\mu_X)^2 +(Y- \mu_Y)^2+2(X-\mu_X)(Y- \mu_Y)]\\$Since we have shown that expectation is linear$\\=E(X-\mu_X)^2 +E(Y- \mu_Y)^2+2E(X-\mu_X)(Y- \mu_Y)]\\=E[(X-E(X)]^2 +E[Y- E(Y)]^2+2Cov (X,Y)$

Since X and Y are independent, Cov(X,Y)=0

$=Var(X)+Var(Y)$

Therefore as required:

$Var(X+Y)=Var(X)+Var(Y)$

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3 years ago

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Travka [436]

Answer:

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6 0

3 years ago

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Which operation involving complex numbers requires the use of a conjugate to be carried out?

Pani-rosa [81]

Answer:

The correct answer will be "Division".

Step-by-step explanation:

The procedure represents numerous values requiring something like a conjugate to have been done becomes division, since the denominator conjugate multiplies the numeric values including its quotient to represent the quotient of several complex numbers throughout the standard language.
It is indeed a method used to separate a set of items across equal proportions.

3 0

3 years ago

Factor by grouping 2u^3+3u^2-14u-21

mariarad [96]

$\bf 2u^3+3u^2-14u-21\implies (2u^3+3u^2)-(14u+21)
\\\\\\
u^2(2u+3)-7(2u+3)\implies \stackrel{\stackrel{common}{factor}}{(2u+3)}(u^2-7)$