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2 years ago

Solve this system of equations using the substitution method. If the system of equations

Mathematics

1 answer:

sleet_krkn [62]2 years ago

3 0

Answer:

well i dont really get ehat yours saying but the qustions are

3x+y=5

3^1+1=5

and then

4z+2y=20

i think

4^6+2^6=20

Step-by-step explanation:

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If you roll the six sided dice six times, are you guaranteed to get a sum of 7 once? answer

BlackZzzverrR [31]

Yes it can be guaranteed to get a sum of 7 once

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3 years ago

Brainliest if correct

kvv77 [185]

Answer:

2/13

Step-by-step explanation:

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2 years ago

Read 2 more answers

Consider a discrete random variable x with pmf px (1) = c 3 ; px (2) = c 6 ; px (5) = c 3 and 0 otherwise, where c is a positive

PtichkaEL [24]

Looks like the PMF is supposed to be

$\mathbb P(X=x)=\begin{cases}\dfrac c3&\text{for }x\in\{1,5\}\\\\\dfrac c6&\text{for }x=2\\\\0&\text{otherwise}\end{cases}$

which is kinda weird, but it's not entirely clear what you meant...

Anyway, assuming the PMF above, for this to be a valid PMF, we need the probabilities of all events to sum to 1:

$\displaystyle\sum_{x\in\{1,2,5\}}\mathbb P(X=x)=\dfrac c3+\dfrac c6+\dfrac c3=\dfrac{5c}6=1\implies c=\dfrac65$

Next,

$\mathbb P(X>2)=\mathbb P(X=5)=\dfrac c3=\dfrac25$

$\mathbb E(X)=\displaystyle\sum_{x\in\{1,2,5\}}x\,\mathbb P(X=x)=\dfrac c3+\dfrac{2c}6+\dfrac{5c}3=\dfrac{7c}3=\dfrac{14}5$

$\mathbb V(X)=\mathbb E\bigg((X-\mathbb E(X))^2\bigg)=\mathbb E(X^2)-\mathbb E(X)^2$
$\mathbb E(X^2)=\displaystyle\sum_{x\in\{1,2,5\}}x^2\,\mathbb P(X=x)=\dfrac c3+\dfrac{4c}6+\dfrac{25c}3=\dfrac{28c}3=\dfrac{56}5$
$\implies\mathbb V(X)=\dfrac{56}5-\left(\dfrac{14}5\right)^2=\dfrac{84}{25}$

If $Y=X^2+1$ , then $X^2=Y-1\implies X=\sqrt{Y-1}$ , where we take the positive root because we know $X$ can only take on positive values, namely 1, 2, and 5. Correspondingly, we know that $Y$ can take on the values $1^2+1=2$ , $2^2+1=5$ , and $5^2+1=26$ . At these values of $Y$ , we would have the same probability as we did for the respective value of $X$ . That is,

$\mathbb P(Y=y)=\begin{cases}\dfrac c3&\text{for }y=2\\\\\dfrac c6&\text{for }y=5\\\\\dfrac c3&\text{for }y=26\\\\0&\text{otherwise}\end{cases}$

Part (5) is incomplete, so I'll stop here.

8 0

3 years ago

The sum of 3 consecutive integers is 120. What is the greatest of these integers? HELP ME IT'S DUE TODAY!!!

kirill115 [55]

Answer:

Step-by-step explanation:

The consecutive integers are increasing by 1

x ← the smallest integer

x+1 ← the middle integer

x+1+1 = x+2 ← the largest integer

x + x+1 + x+2 = 120

3x + 3 = 120

÷3 ÷3

x + 1 = 40

-1 -1

x = 39

x+2 = 39 + 2 = 41

3 0

2 years ago

If A = James's present age, write an expression for his age seven years from now.

ehidna [41]

<span>If A = James's present age
then
</span><span>his age seven years from now = A - 7

hope it helps</span>

3 0

2 years ago