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4 years ago

Evaluate the expression 2x^2 - x, when x = -3. Show all steps.

Mathematics

2 answers:

Alex_Xolod [135]4 years ago

5 0

Answer:

Step-by-step explanation:

2x² - x

2(-3)² - (-3)

2(9) + 3

18 + 3

V125BC [204]4 years ago

4 0

Answer:

Step-by-step explanation:

This is a substitution question,we are to substitute a given value in place of a certain letter

So let's solve

2x^2-x

And since x is given to be -3

So let's substitute

2(-3)^2-(-3)

2(9)-(-3)

18+3

So the final answer is 21

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In a survey at a local college, 18% of students reported that they do not own a mobile device with internet capabilities. if 20

Sholpan [36]

Answer:

0.64

Step-by-step explanation:

The probability that randomly selected student doesn't own a mobile device with internet capabilities is $p=0.18$ and the probability that randomly selected student owns a mobile device with internet capabilities is $q=1-p=1-0.18=0.82.$

If 20 students are selected at random, the probability that at most 5 students (0 students, 1 student, 2 students, 3 students, 4 students or 5 students) don't own a mobile device with internet capabilities is

$Pr=C_{20}^0p^0q^{20}+C_{20}^1p^1q^{19}+C_{20}^2p^2q^{18}+C_{20}^3p^3q^{17}+C_{20}^4p^4q^{16}+C_{20}^5p^5q^{15}=q^{20}+20pq^{19}+190p^2q^{18}+1,140p^3q^{17}+4,875p^4q^{16}+15,504p^5q^{15}\approx 0.6405021423\approx 0.64.$

3 0

3 years ago

I need help ASAP im very confused on the box part I put the two on the top but then what else?

r-ruslan [8.4K]

Answer is in the file below

tinyurl.com/wpazsebu

8 0

3 years ago

Read 2 more answers

Given the piecewise function shown, find the value of h(–6). A) 1 B) 26 C) -23 D) -6

kirza4 [7]

Answer:

-22

Step-by-step explanation:

Which part of the function is valid when x = -6

The first part

h(-6) = 4x+2 and let x = -6

=4(-6) +2

= -24 +2

=-22

5 0

3 years ago

Which proportion can be used to show that the slope of JL is equal to the slope of MP

Ilya [14]

Answer:

See below and attached

Step-by-step explanation:

As per the graph we have:

Coordinates of JL are J(-7, 4), L(-4, 0)

Coordinates of MP are M(-10, 8), P(-1, -4)

Slope formula is:

m = (y₂ - y₁)/(x₂ - x₁)

Slope of JL:

(0 - 4)/(-4-(-7)) = - 4 / 3

Slope of MP:

(-4 -8)/(-1- (-10)) = -12 / 9 = - 4/3

5 0

3 years ago

Suppose the horses in a large stable have a mean weight of 1467lbs, and a standard deviation of 93lbs. What is the probability t

krok68 [10]

Answer:

0.5034 = 50.34% probability that the mean weight of the sample of horses would differ from the population mean by less than 9lbs if 49 horses are sampled at random from the stable

Step-by-step explanation:

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

Normal probability distribution

Problems of normally distributed samples are solved using 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.

In this problem, we have that:

$\mu = 1467, \sigma = 93, n = 49, s = \frac{93}{\sqrt{49}} = 13.2857$

What is the probability that the mean weight of the sample of horses would differ from the population mean by less than 9lbs if 49 horses are sampled at random from the stable?

This is the pvalue of Z when X = 1467 + 9 = 1476 subtracted by the pvalue of Z when X = 1467 - 9 = 1458.

X = 1476

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

By the Central Limit Theorem

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

$Z = \frac{1476 - 1467}{13.2857}$

$Z = 0.68$

$Z = 0.68$ has a pvalue of 0.7517

X = 1458

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

$Z = \frac{1458 - 1467}{13.2857}$

$Z = -0.68$

$Z = -0.68$ has a pvalue of 0.2483

0.7517 - 0.2483 = 0.5034

0.5034 = 50.34% probability that the mean weight of the sample of horses would differ from the population mean by less than 9lbs if 49 horses are sampled at random from the stable

5 0

3 years ago