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3 years ago

Simpifly (-5x2 - 3x - 7) + (-2x3 + 6x2 - 8)

Mathematics

2 answers:

klasskru [66]3 years ago

6 0

Answer:

-2x³ + x² - 3x - 15

Step-by-step explanation:

Simply combine like terms together:

-5x² - 3x - 7 - 2x³ + 6x² - 8

-2x³ + (-5x² + 6x²) - 3x + (-7 - 8)

-2x³ + x² - 3x + (-7 - 8)

-2x³ + x² - 3x - 15

Scrat [10]3 years ago

6 0

Answer: -2x^3+x^2-3x-15

Step-by-step explanation:

As there is only addition and subtraction here, and the two groups of parenthesis are added, you can ignore the parenthesis.

Thus, simply combine like terms to get.

-2x^3+x^2-3x-15

Hope it helps <3

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Solving multi step equations : 3.4 +0.5y + 1.1 = -4.5

elena-s [515]

3.4+0.5y +1.1=-4.5

3.4+1.1+0.5y= -4.5

4.5+0.5y=-4.5

move 4.5 to the other side

sign changes from +4.5 to -4.5

4.5-4.5+0.5y= -4.5-4.5

0.5y= -4.5-4.5

0.5y=-9

divide both sides by 0.5

0.5y/0.5= -9/0.5

Answer: y= -18

3 0

3 years ago

The amount of money spent on textbooks per year for students is approximately normal.

Contact [7]

Answer:

(A) A 95% confidence for the population mean is [$332.16, $447.84] .

(B) If the confidence level in part (a) changed from 95% to 99%, then the margin of error for the confidence interval would increase.

(C) If the sample size in part (a) changed from 19 to 22, then the margin of error for the confidence interval would decrease.

(D) A 99% confidence interval for the proportion of students who purchase used textbooks is [0.363, 0.477] .

Step-by-step explanation:

We are given that 19 students are randomly selected the sample mean was $390 and the standard deviation was $120.

Firstly, the pivotal quantity for finding the confidence interval for the population mean is given by;

P.Q. = $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample mean = $390

s = sample standard deviation = $120

n = sample of students = 19

$\mu$ = population mean

Here for constructing a 95% confidence interval we have used a One-sample t-test statistics because we don't know about population standard deviation.

So, 95% confidence interval for the population mean, $\mu$ is ;

P(-2.101 < $t_1_8$ < 2.101) = 0.95 {As the critical value of t at 18 degrees of

freedom are -2.101 & 2.101 with P = 2.5%}

P(-2.101 < $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ < 2.101) = 0.95

P( $-2.101 \times {\frac{s}{\sqrt{n} } }$ < ${\bar X-\mu}$ < $2.101 \times {\frac{s}{\sqrt{n} } }$ ) = 0.95

P( $\bar X-2.101 \times {\frac{s}{\sqrt{n} } }$ < $\mu$ < $\bar X+2.101 \times {\frac{s}{\sqrt{n} } }$ ) = 0.95

95% confidence interval for $\mu$ = [ $\bar X-2.101 \times {\frac{s}{\sqrt{n} } }$ , $\bar X+2.101 \times {\frac{s}{\sqrt{n} } }$ ]

= [ $\$390-2.101 \times {\frac{\$120}{\sqrt{19} } }$ , $\$390+2.101 \times {\frac{\$120}{\sqrt{19} } }$ ]

= [$332.16, $447.84]

(A) Therefore, a 95% confidence for the population mean is [$332.16, $447.84] .

(B) If the confidence level in part (a) changed from 95% to 99%, then the margin of error for the confidence interval which is $Z_(_\frac{\alpha}{2}_) \times \frac{s}{\sqrt{n} }$ would increase because of an increase in the z value.

(C) If the sample size in part (a) changed from 19 to 22, then the margin of error for the confidence interval which is $Z_(_\frac{\alpha}{2}_) \times \frac{s}{\sqrt{n} }$ would decrease because as denominator increases; the whole fraction decreases.

(D) We are given that to estimate the proportion of students who purchase their textbooks used, 500 students were sampled. 210 of these students purchased used textbooks.

Firstly, the pivotal quantity for finding the confidence interval for the population proportion is given by;

P.Q. = $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ~ N(0,1)

where, $\hat p$ = sample proportion students who purchase their used textbooks = $\frac{210}{500}$ = 0.42

n = sample of students = 500

p = population proportion

Here for constructing a 99% confidence interval we have used a One-sample z-test statistics for proportions

So, 99% confidence interval for the population proportion, p is ;

P(-2.58 < N(0,1) < 2.58) = 0.99 {As the critical value of z at 0.5%

level of significance are -2.58 & 2.58}

P(-2.58 < $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < 2.58) = 0.99

P( $-2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < ${\hat p-p}$ < $2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ) = 0.99

P( $\hat p-2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < p < $\hat p+2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ) = 0.99

99% confidence interval for p = [ $\hat p-2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ , $\hat p+2.58 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ]

= [ $0.42 -2.58 \times {\sqrt{\frac{0.42(1-0.42)}{500} } }$ , $0.42 +2.58 \times {\sqrt{\frac{0.42(1-0.42)}{500} } }$ ]

= [0.363, 0.477]

Therefore, a 99% confidence interval for the proportion of students who purchase used textbooks is [0.363, 0.477] .

8 0

3 years ago

I need help with theses questions

Ronch [10]

The relationship of the given angles are:

1. A. Adjacent

2. B. vertical

3. B. vertical

4. E. linear pair

5. C. complementary

6. D. supplementary

7. C. complementary

8. A. adjacent

9. A. adjacent

10. D. supplementary

11. A. adjacent

12. C. complementary.

<h3>How to Determine the Relationship Between Angles?</h3>

Different pairs of angles are related to each other in several ways. The explanation below shows the relationship between the given angles.

1. Angles 2 and 3 share a common vertex and a common side, therefore:

<2 and <3 are: A> Adjacent

2. <3 and <4 are non-adjacent angles that share a common vertex and are opposite each other. Thus:

<3 and <4 are: B. vertical

3. <1 and <3 are: B. vertical

4. <1 and <2 lie on a straight line and are adjacent to each other. Therefore, they are a: linear pair

5. 78 + 12 = 90 degrees. Therefore, their relationship is that they are: C. complementary

6. 123 + 57 = 180. Therefore, they are: D. supplementary

7. Angles a and b form a right angle. Therefore, they are: C. complementary

8. <1 and <2 are: adjacent

9. <3 and <4 are: A. adjacent

10. 90 + 90 = 180, therefore, the angles are: D. supplementary

11. Both angles are: A. adjacent

12. 40 + 50 = 90 degrees. Therefore, the angles are: C. complementary.

Learn more about the relationship of angles on:

brainly.com/question/12591450

#SPJ1

4 0

1 year ago

Select the locations on the number line to plot the points 4 1/3 and −1 1/3.

wel

4 1/3 is the first tiny line after the big line before the 5.

-1 1/3 is count 4 big lines after -5 and one tiny line

4 0

4 years ago

In the figure, m∠2=(20x+52)° and m∠7=(40x-48)°

Taya2010 [7]

Answer: x=5 m is parallel to n

Step-by-step explanation:

∠2 and ∠7 are alternate exterior angles so they are equal.

So you can create the equation

40x-48 = 20x+52 Subtract 20x from both sides. Add 48 to both sides.

20x = 100

x = 5

if you need m∠2 Substtute 5 for x in 20x+52

20(5) + 52 = 100 +52 m∠2= 152°

m∠7 40(5) - 48 = 200-48 m∠7= 152°

3 0

4 years ago