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3 years ago

Find the product of (2x + 5y)(2x − 5y).

Mathematics

2 answers:

Nana76 [90]3 years ago

7 0

The final answer for this is 4x^2-25y^2.

Whitepunk [10]3 years ago

4 0

Answer:

Option D is correct.

the product of $(2x+5y)(2x-5y)$ is, $4x^2-25y^2$

Step-by-step explanation:

Using identity rule:

$(a+b)(a-b) = a^2-b^2$

To find the product of:

$(2x+5y)(2x-5y)$

Apply the identity rule:

here, a = 2x and b = 5y then

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

= $4x^2-25y^2$

Therefore, the product of $(2x+5y)(2x-5y)$ is, $4x^2-25y^2$

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3 years ago

Read 2 more answers

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Lets dive into the problem, starting with the equation for volume; length x width x height.

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3 years ago

In a random sample of 80 teenagers, the average number of texts handled in a day is 50. The 96% confidence interval for the mean

Nastasia [14]

Answer:

a) $\bar X =\frac{46+54}{2}=50$

And the margin of error is given by:

$ME= \frac{54-46}{2}= 4$

The confidence level is 0.96 and the significance level is $\alpha=1-0.96=0.04$ and the value of $\alpha/2 =0.02$ and the margin of error is given by:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$

We can calculate the critical value and we got:

$z_{\alpha/2} = 2.05$

And if we solve for the deviation like this:

$\sigma = ME * \frac{\sqrt{n}}{z_{\alpha/2}}$

And replacing we got:

$\sigma =4 *\frac{\sqrt{80}}{2.05} =17.45$

b) $ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}=2.05 *\frac{17.45}{\sqrt{160}}=2.828$

And as we can see that the margin of error would be lower than the original value of 4, the margin of error would be reduced by a factor $\sqrt{2}$

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

$\bar X$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma$ represent the population standard deviation

n=80 represent the sample size

Solution to the problem

Part a

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

For this case we can calculate the mean like this:

$\bar X =\frac{46+54}{2}=50$

And the margin of error is given by:

$ME= \frac{54-46}{2}= 4$

The confidence level is 0.96 and the significance level is $\alpha=1-0.96=0.04$ and the value of $\alpha/2 =0.02$ and the margin of error is given by:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$

We can calculate the critical value and we got:

$z_{\alpha/2} = 2.05$

And if we solve for the deviation like this:

$\sigma = ME * \frac{\sqrt{n}}{z_{\alpha/2}}$

And replacing we got:

$\sigma =4 *\frac{\sqrt{80}}{2.05} =17.45$

Part b

For this case is the sample size is doubled the margin of error would be:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}=2.05 *\frac{17.45}{\sqrt{160}}=2.828$

And as we can see that the margin of error would be lower than the original value of 4, the margin of error would be reduced by a factor $\sqrt{2}$

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3 years ago

Find the value of x. 7 D 3 B В х С X =

bekas [8.4K]

Answer:

x = $\sqrt{30}$

Step-by-step explanation:

Using the Altitude- on- Hypotenuse theorem

(leg of Δ ABC )² = (part of hypotenuse below it ) × ( whole hypotenuse )

x² = 3 × (3 + 7) = 3 × 10 = 30 ( take the square root of both sides )

x = $\sqrt{30}$

7 0

3 years ago