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Troyanec [42]
3 years ago
14

Twice the sum of a number and 2 is equal to three times the difference of the number and 7.Find the number.

Mathematics
1 answer:
Law Incorporation [45]3 years ago
4 0

Answer:

the best choice would be b.


Step-by-step explanation:


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Which equation can be used to determine the distance between the origin and (-2,-4)?
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Answer:

I believe it is the second 1

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PLEASE PLEEASE HELP I PROMISE I WILL GIVE BRAINLIIEST!!!!
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76, the middle one

Step-by-step explanation:

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a boat traveled at an average speed of 14.4 km/h for 3.5 hours. how far did the boat travel? use d=rt.
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Answer is in the attachment below.

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3 years ago
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Let X1, X2, ... , Xn be a random sample from N(μ, σ2), where the mean θ = μ is such that −[infinity] < θ < [infinity] and
Sliva [168]

Answer:

l'(\theta) = \frac{1}{\sigma^2} \sum_{i=1}^n (X_i -\theta)

And then the maximum occurs when l'(\theta) = 0, and that is only satisfied if and only if:

\hat \theta = \bar X

Step-by-step explanation:

For this case we have a random sample X_1 ,X_2,...,X_n where X_i \sim N(\mu=\theta, \sigma) where \sigma is fixed. And we want to show that the maximum likehood estimator for \theta = \bar X.

The first step is obtain the probability distribution function for the random variable X. For this case each X_i , i=1,...n have the following density function:

f(x_i | \theta,\sigma^2) = \frac{1}{\sqrt{2\pi}\sigma} exp^{-\frac{(x-\theta)^2}{2\sigma^2}} , -\infty \leq x \leq \infty

The likehood function is given by:

L(\theta) = \prod_{i=1}^n f(x_i)

Assuming independence between the random sample, and replacing the density function we have this:

L(\theta) = (\frac{1}{\sqrt{2\pi \sigma^2}})^n exp (-\frac{1}{2\sigma^2} \sum_{i=1}^n (X_i-\theta)^2)

Taking the natural log on btoh sides we got:

l(\theta) = -\frac{n}{2} ln(\sqrt{2\pi\sigma^2}) - \frac{1}{2\sigma^2} \sum_{i=1}^n (X_i -\theta)^2

Now if we take the derivate respect \theta we will see this:

l'(\theta) = \frac{1}{\sigma^2} \sum_{i=1}^n (X_i -\theta)

And then the maximum occurs when l'(\theta) = 0, and that is only satisfied if and only if:

\hat \theta = \bar X

6 0
3 years ago
8 (3x + 6) + 168<br> Can you help me?
Rom4ik [11]

Answer: 24x + 216

Step-by-step explanation:

8(3x+6)+168

Distribute:

(8)(3x)+(8)(6)+168

24x+48+168

Combine terms:

(24x)+(48+168)

=24x+216

3 0
3 years ago
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