Discriminant of 2x2 - 4x + 7 = 0

HELP PLEASE ASAP!!! 50 points

neonofarm [45]

Answer:

(a+b,c)

Step-by-step explanation:

Note that the midpoint formula is:

$(\frac{x_{1} +x_{2}}{2}, \frac{y_{1} +y_{2}}{2})$

Point A (0,0) and Point C (2a+2b,2c)

It follows that:

$(\frac{(2a+2b +0}{2}, \frac{2c+0}{2})\\(\frac{(2(a+b)}{2}, \frac{2c}{2})\\\\(a+b,c)$

3 0

3 years ago

Read 2 more answers

The midpoint of AB is M(1, -1). If the coordinates of A are (7,-4), what are the

Lapatulllka [165]

Answer:

work is attached and shown

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3 years ago

The price of a 40-inch television is $268 plus 8% sales tax rate. What is the amount of the sales tax for the television, in dol

Harlamova29_29 [7]

$268.00 base price
8% is $21.44
Total with tax $289.44

3 0

2 years ago

There are 48 students in an elementary statistics class. On the basis of years of experience, the instructor knows that the time

Stella [2.4K]

Answer:

a) 64.06% probability that he is through grading before the 11:00 P.M. TV news begins.

b) The hardness distribution is not given. But you would have to find s when n = 39, then the probability would be 1 subtracted by the pvalue of Z when X = 51.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

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.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For the sum of n trials, the mean is $\mu*n$ and the standard deviation is $s = \sigma\sqrt{n}$

In this question:

$n = 48, \mu = 48*5 = 240, s = 4\sqrt{48} = 27.71$

These values are in minutes.

(a) If grading times are independent and the instructor begins grading at 6:50 P.M. and grades continuously, what is the (approximate) probability that he is through grading before the 11:00 P.M. TV news begins?

From 6:50 PM to 11 PM there are 4 hours and 10 minutes, so 4*60 + 10 = 250 minutes. This probability is the pvalue of Z when X = 250. So

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

By the Central Limit Theorem

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

$Z = \frac{250 - 240}{27.71}$

$Z = 0.36$

$Z = 0.36$ has a pvalue of 0.6406

64.06% probability that he is through grading before the 11:00 P.M. TV news begins.

(b) What is the (approximate) probability that the sample mean hardness for a random sample of 39 pins is at least 51?

The hardness distribution is not given. But you would have to find s when n = 39(using the standard deviation of the population divided by the square root of 39, since it is not a sum here), then the probability would be 1 subtracted by the pvalue of Z when X = 51.

5 0

3 years ago

Sviatoslav solved the quadratic equation x^2-x-1=0 by completing the square. In the process, he came up with the equivalent equa

zimovet [89]

Answer:

$x=\frac{1+\sqrt5}{2}$ and $x=\frac{1-\sqrt5}{2}$