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3 years ago

Simplify (7x-1)(2x+5)

2 answers:

6 0

$\text{Simplify by using FOIL}\\\\\text{(First, Outside, Inside, Last}\\\\\text{Solve:}\\\\(7x-1)(2x+5)\\\\(7x)(2x)+(7x)(5)+(-1)(2x)+(-1)(5)\\\\14x^2+35x-2x-5\\\\\text{Combine like terms}\\\\\boxed{14x^2+33x-5}$

Alex73 [517]3 years ago

5 0

Step-by-step explanation:

$(7x-1)(2x+5) = 0 \\ 14x {}^{2} + 35x - 2x - 5 = 0 \\ 14x {}^{2} + 33x - 5 = 0 \\$

now,

$14 {x}^{2} - 2x + 35x - 5 = 0 \\ 2x(7x - 1) + 5(7x - 1) = 0 \\ (2x + 5)(7x - 1) = 0 \\ 2x + 5 = 0 \: \: \: \: or \: \: \: \: \: 7x - 1 = 0 \\ \\ x = - \frac{5}{2} \: \: \: \: or \: \: \: \: x = \frac{1}{7}$

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The estimated daily living costs for an executive traveling to various major cities follow. The estimates include a single room

Alexandra [31]

Answer:

$\bar x = 260.1615$

$\sigma = 70.69$

The confidence interval of standard deviation is: $53.76$ to $103.25$

Step-by-step explanation:

Given

$n =20$

See attachment for the formatted data

Solving (a): The mean

This is calculated as:

$\bar x = \frac{\sum x}{n}$

So, we have:

$\bar x = \frac{242.87 +212.00 +260.93 +284.08 +194.19 +139.16 +260.76 +436.72 +355.36 +.....+250.61}{20}$

$\bar x = \frac{5203.23}{20}$

$\bar x = 260.1615$

$\bar x = 260.16$

Solving (b): The standard deviation

This is calculated as:

$\sigma = \sqrt{\frac{\sum(x - \bar x)^2}{n-1}}$

$\sigma = \sqrt{\frac{(242.87 - 260.1615)^2 +(212.00- 260.1615)^2+(260.93- 260.1615)^2+(284.08- 260.1615)^2+.....+(250.61- 260.1615)^2}{20 - 1}}$ $\sigma = \sqrt{\frac{94938.80}{19}}$

$\sigma = \sqrt{4996.78}$

$\sigma = 70.69$ --- approximated

Solving (c): 95% confidence interval of standard deviation

We have:

$c =0.95$

So:

$\alpha = 1 -c$

$\alpha = 1 -0.95$

$\alpha = 0.05$

Calculate the degree of freedom (df)

$df = n -1$

$df = 20 -1$

$df = 19$

Determine the critical value at row $df = 19$ and columns $\frac{\alpha}{2}$ and $1 -\frac{\alpha}{2}$

So, we have:

$X^2_{0.025} = 32.852$ ---- at $\frac{\alpha}{2}$

$X^2_{0.975} = 8.907$ --- at $1 -\frac{\alpha}{2}$

So, the confidence interval of the standard deviation is:

$\sigma * \sqrt{\frac{n - 1}{X^2_{\alpha/2} }$ to $\sigma * \sqrt{\frac{n - 1}{X^2_{1 -\alpha/2} }$

$70.69 * \sqrt{\frac{20 - 1}{32.852}$ to $70.69 * \sqrt{\frac{20 - 1}{8.907}$

$70.69 * \sqrt{\frac{19}{32.852}$ to $70.69 * \sqrt{\frac{19}{8.907}$

$53.76$ to $103.25$

8 0

3 years ago

What is the measure of ABC?<br> A. 130<br> B. 85<br> C.40<br> D.170

Nitella [24]

Answer:

130

Step-by-step explanation:

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professor190 [17]

567

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3 years ago

Find the product of 487.9573 and 1,000.

maria [59]

487.9573 * 1000 = 487947.30

As you can see, the first number has a decimal point, and the second number is 1000. You can drop the 0s in the 1000 leaving 1 to multiply with the first number. Simply move the decimal point to the right based on the number of 0s there are on the second number.

Since, 1000 has three 0s. Move the decimal point 3 times to the right of the number. So, from 487.9573 to 487957.3

If the function is division but the numbers are the same, you must move the decimal point to the left.

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3 years ago

Which of the following expressions is not equivalent to -5?

Elena L [17]

Answer:

-5/25

Step-by-step explanation:

25/(-5)=-5

-35/7=-5

-5/25=-1/5

35/(-7)=-5

hope I helped

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3 years ago

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