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3 years ago

What are the x-intercepts of the equation? y=x2−9x2−16

Mathematics

2 answers:

solmaris [256]3 years ago

8 0

Answer:

x = 17

Step-by-step explanation:

$y = x2 - 9 \times 2 - 16$

$0 = 2x - 18 - 16$

$0 = 2x - 34$

$- 2x = - 34$

$x = 17$

alisha [4.7K]3 years ago

4 0

X=17 !

let’s just pretend this is 20 characters long

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2. In your own words, explain HOW to find the standard deviation of this data set. (20 points) 3. What does the standard deviati

Ket [755]

Answer:

$\sigma = 11.28$ --- Standard deviation

Step-by-step explanation:

Given

See attachment for graph

Solving (a): Explain how the standard deviation is calculated.

<u>Start by calculating the mean</u>

To do this, we divide the sum of the products of grade and number of students by the total number of students;

i.e.

$\bar x = \frac{\sum fx}{\sum f}$

So, we have:

$\bar x = \frac{50 * 1 + 57 * 2 + 60 * 4 + 65 * 3 +72 *3 + 75 * 12 + 77 * 10 + 81 * 6 + 83 * 6 + 88 * 9 + 90 * 12 + 92 * 12 +95 * 2 + 99 * 4 + 100 * 5}{1 + 2 + 4 + 3 +3 + 12 + 10 + 6 + 6 + 9 + 12 + 12 +2 + 4 + 5}$

$\bar x = \frac{7531}{91}$

$\bar x = 82.76$

Next, calculate the variance using the following formula:

$\sigma^2 = \frac{\sum f(x - \bar x)^2}{\sum f}$

i.e subtract the mean from each dataset; take the squares; add up the squares; then divide the sum by the number of dataset

So, we have:

$\sigma^2 = \frac{1 * (50 - 82.76)^2 +...................+ 5 * (100 - 82.76)^2}{91}$

$\sigma^2 = \frac{11580.6816}{91}$

$\sigma^2 = 127.26$

Lastly, take the square root of the variance to get the standard deviation

$\sigma = \sqrt{\sigma^2}$

$\sigma = \sqrt{127.26}$

$\sigma = 11.28$ --- approximated

<em>Hence, the standard deviation is approximately 11.28</em>

Considering the calculated mean (i.e. 82.76), the standard deviation (i.e. 11.28) is small and this means that the grade of the students are close to the average grade.

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3 years ago

Hope someone help.me

zvonat [6]

x = r sin θ cos Ф

x² = r² sin² θ cos² Ф

y = r sin θ sin Ф

y² = r² sin² θ sin² Ф

z = r cos θ

z² = r² cos² θ

x² + y² + z²

= r² sin² θ cos² Ф + r² sin² θ sin² Ф + r² cos² θ

= r² sin² θ (cos² Ф + sin² Ф) + r² cos² θ

= r² sin² θ + r² cos² θ

= r² (sin² θ + cos² θ)

= r² √

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3 years ago

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lesya692 [45]

Answer:

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Step-by-step explanation:

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