All categories

3 years ago

I have a question that has already been answered. I just need someone to please explain the steps.

Mathematics

1 answer:

Jobisdone [24]3 years ago

8 0

Answer:

Step-by-step explanation:

Using brackets will really help.

y = (x^2 + 4x + ... ) - 5 You are trying to complete the square. The square in this case is a trinomial that is squared.

To do that, you take 1/2 the linear term (4x)/2, drop the x (4/2), and square the result (4/2)^2. The number is 2^2 which is 4.

So far what you have is

y = (x^2 + 4x + 4) - 5

Now you just can't add 4 without adjusting it somehow. If you do, the whole question will change it's value. Because you added 4 inside the brackets, you must subtract 4 outside the brackets.

What that means is 4 inside - 4 outside. So it looks like this

y = (x^2 + 4x + 4) - 5 - 4

Now you continue on

y = (x + 2)^2 - 9 The 4 combines with the 5 to make nine.

You might be interested in

You are choosing between two different cell phone plans. The first plan charges a rate of

Zolol [24]

Answer:

at least 450 minutes

Step-by-step explanation:

Find an expression for the cost of each plan as a function of the number of minutes. Set the expressions equal to each other, and solve for the number of minutes.

Let x = number of minutes.

First plan:

cost (in dollars) = 0.21x

Second plan:

cost (in dollars) = 0.11x + 44.95

Set the expressions equal:

0.21x = 0.11x + 44.95

Subtract 0.11x from both sides.

0.1x = 44.95

Divide both sides by 0.1

x = 44.95/0.1

x = 449.5

Since you cannot have a fraction of a minute, the answer is 450 minutes.

3 0

2 years ago

The lifetime of LCD TV sets follows an exponential distribution with a mean of 100,000 hours. Compute the probability a televisi

kondaur [170]

Answer:

0.9

0.3012

0.1809

230258.5

Step-by-step explanation:

Given that:

μ = 100,000

λ = 1/μ = 1 / 100000 = 0.00001

a. Fails in less than 10,000 hours.

P(X < 10,000) = 1 - e^-λx

x = 10,000

P(X < 10,000) = 1 - e^-(0.00001 * 10000)

= 1 - e^-0.1

= 1 - 0.1

= 0.9

b. Lasts more than 120,000 hours.

X more than 120000

P(X > 120,000) = e^-λx

P(X > 120,000) = e^-(0.00001 * 120000)

P(X > 120,000) = e^-1.2

= 0.3011942 = 0.3012

c. Fails between 60,000 and 100,000 hours of use.

P(X < 60000) = 1 - e^-λx

x = 60000

P(X < 60,000) = 1 - e^-(0.00001 * 60000)

= 1 - e-^-0.6

= 1 - 0.5488116

= 0.4511883

P(X < 100000) = 1 - e^-λx

x = 100000

P(X < 60,000) = 1 - e^-(0.00001 * 100000)

= 1 - e^-1

= 1 - 0.3678794

= 0.6321205

Hence,

0.6321205 - 0.4511883 = 0.1809322

d. Find the 90th percentile. So 10 percent of the TV sets last more than what length of time?

P(x > x) = 10% = 0.1

P(x > x) = e^-λx

0.1 = e^-0.00001 * x

Take the In

−2.302585 = - 0.00001x

2.302585 / 0.00001

= 230258.5

3 0

3 years ago

suppose X and Y are independent random variables, both with normal distributions. If X has a mean of 45 with a standard deviatio

djyliett [7]

Answer:

0.9772 = 97.72% probability that a randomly generated value of X is greater than a randomly generated value of Y

Step-by-step explanation:

When the distribution is normal, we use the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question:

$\mu_X = 45, \sigma_X = 4, \mu_Y = 35, \sigma_Y = 3$

What is the probability that a randomly generated value of X is greater than a randomly generated value of Y

This means that the subtraction of X by Y has to be positive.

When we subtract two normal variables, the mean is the subtraction of their means, and the standard deviation is the square root of the sum of their variances. So

$\mu = \mu_X - \mu_Y = 45 - 35 = 0$

$\sigma = \sqrt{\sigma_X^2+\sigma_Y^2} = \sqrt{25} = 5$

We want to find P(X > 0), that is, 1 subtracted by the pvalue of Z when X = 0. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{0 - 10}{5}$

$Z = -2$

$Z = -2$ has a pvalue of 0.0228

1 - 0.0228 = 0.9772

0.9772 = 97.72% probability that a randomly generated value of X is greater than a randomly generated value of Y

4 0

3 years ago

5 is 5% of what number w

navik [9.2K]

5 = 0.05w
5 / 0.05 = w
100 = w........5 is 5% of 100

3 0

3 years ago

Read 2 more answers

Factor of 169 and 9 squared

emmasim [6.3K]

Answer:

The greatest common factor of 169 and 81 is 1.

Step-by-step explanation:

9 squared is 81 and the greatest common factor of 169 and 81 is one. They have no other common factors. Please mark me brainliest and I hope this helps!

3 0

3 years ago