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2 years ago

14x=x^2-15 find the value of x

Mathematics

1 answer:

hram777 [196]2 years ago

5 0

Answer: $x=-1, 15$

Step-by-step explanation:

$x^2 -14x-15=0\\\\(x-15)(x+1)=0\\\\x=-1, 15$

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What is 5s-9<2s+12

IRINA_888 [86]

$5s-9 < 2s+12\ \ \ \ \ |\text{add 9 to both sides}\\\\5s < 2s+21\ \ \ \ |\text{subtract 2s from both sides}\\\\3s < 21\ \ \ \ |\text{divide both sides by 3}\\\\\boxed{x < 7\to s\in(-\infty,\ 7)}$

5 0

3 years ago

g If a random sample of 18 deliveries was selected instead and the standard deviation of these delivery times was found to be 9.

lana [24]

Answer:

We can use the z score formula given by:

$z= \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

If we use this formula we got:

$z=\frac{21-20}{\frac{9.31}{\sqrt{18}}}= 0.456$

$z=\frac{25-20}{\frac{9.31}{\sqrt{18}}}= 2.279$

And using a calculator, excel or the normal standard table and we have that:

$P(0.456$

Step-by-step explanation:

We assume this previous info: It is known that the amounts of time required for room-service delivery at a certain Marriott Hotel are Normally distributed with the average delivery time of 20 minutes.

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the delivery times of a population, and for this case we know the distribution for X is given by:

$X \sim N(20,9.31)$

Where $\mu=20$ and $\sigma=9.31$

Since the distribution for X is normal then the distribution for the sample mean $\bar X$ is given by:

$\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})$

And we can use the z score formula given by:

$z= \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

If we use this formula we got:

$z=\frac{21-20}{\frac{9.31}{\sqrt{18}}}= 0.456$

$z=\frac{25-20}{\frac{9.31}{\sqrt{18}}}= 2.279$

And using a calculator, excel or the normal standard table and we have that:

$P(0.456$

6 0

4 years ago

A number decrease by the square of 9

ratelena [41]

X-9^2
a number = x
decreased= subtracting
square of 9= 9^2

7 0

3 years ago

Solve the equation for x, where x is a real number (5 points): <br> -2x^2 + 7x + 7 = 6

Artemon [7]

Start by doing a subtraction of 6 to both sides so that the equation becomes -2x^2 + 7x + 1 = 0.
To find the solutions to this equation, we can apply the quadratic formula. This quadratic formula solves equations of the form ax^2 + bx + c = 0
                             x = [ -b ± √(b^2 - 4ac) ] / (2a)
                             x = [ -7 ± √((7)^2 - 4(-2)(1)) ] / ( 2(-2) )
                             x = [-7 ± √(49 - (-8) ) ] / ( -4 )
                             x = [-7 ± √(57) ] / ( -4)
                             x = [-7 ± sqrt(57) ] / ( -4 )
                             x = 7/4 ± -sqrt(57)/4
The answers are 7/4 + sqrt(57)/4 and 7/4 - sqrt(57)/4.

8 0

3 years ago

Read 2 more answers

Express your answer in the lowest terms. -1/10-(-8/10)

Zielflug [23.3K]

The exact form is 7/10
Decimal for is 0.7

8 0

3 years ago