If using the method of completing the square to solve the quadratic equation

HELP! SHOW YOUR WORK! 2 2/7 - 5 5/7

konstantin123 [22]

Answer:

-24/7

Step-by-step explanation:

change the number to improper fractions:

2 2/7 - 16/7

5 5/7 - 40/7

now since they wont make a positive number, you can do 40-16 which is 24 so your answer is -24/7

NEGATIVE 24/7

4 0

3 years ago

Read 2 more answers

Please answer correctly , will mark brainliest answer !!!

Paladinen [302]

Answer:

x + 18 + 28/x

Step-by-step explanation:

You first have to factor the expression that represents the area using the AC method.

When done factoring, you should get the expression (x + 4)(x + 7).

From there you divide that by x + 7 to get the length

(x + 4)(x + 7) / x + 7 = x + 18 + 28/x.

This may not be the correct answer, but I believe this is correct.

If you wish to do it quicker, you can just divide the entire expression of the area by the expression of the length, but if you were writing it down on paper, I suggest factoring it out.

8 0

3 years ago

Heather has $500 in her savings account. She withdraws $20 per week for gas. Write an equation Heather can use to see how many w

tatuchka [14]

Since she has a base amount of $500, that will be your y-intercept. 20 is going to be your slope, and since she's withdrawing it, it will be -20. Here's how the equation would be set up (in y = mx + b):

-20x + 500 = 220

*Subtract 500 from both sides*

-20x = -280

*Divide both sides by -20*

x = 14.

Therefore, it will take 14 weeks.

7 0

3 years ago

Read 2 more answers

In 2010, the Census Bureau estimated the proportion of all Americans who own their homes to be 0.669. An urban economist wants t

Alexxandr [17]

Answer:

i)

Sample size making use of the Census Bureau: 1,499 American adults.

Sample size without making use of the Census Bureau: 1,692 American adults

ii)

71

Step-by-step explanation:

i)

The sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

z = 1.645 is the critical value for a 90% confidence level (*) 

p= 0.669 is the population proportion given by the Census

e = 0.02 is the margin of error

so

$\bf n=\frac{(1.645)^2*0.669*0.331}{0.02^2}=1,498.05\approx 1,499$

rounded up to the nearest integer.

(*)This is a point z such that the area under the Normal curve N(0,1) 1nside the interval [-z, z] equals 90% = 0.9

It can be obtained with tables or in Excel or OpenOffice Calc with

NORMSINV(0.95)

If she ignores the Census estimate, the she has to take the largest sample possible that meets the requirements.

Let's show it is obtained when p = 0.5

As we said, the sample size n is

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

e = 0.02 is the error proportion

z = 1.645

hence

$\bf n=\frac{(1.645)^2p(1-p)}{(0.02)^2}=6765.0625p(1-p)=6765.0625p-6765.0625p^2$

taking the derivative with respect to p, we get

n'(p)=6765.0625-2*6765.0625p

and

n'(p) = 0 when p=0.5

By taking the second derivative we see n''(p)<0, so p=0.5 is a maximum of n

This means that if we set p=0.5, we get the maximum sample size for the confidence level required for the proportion error 0.02

Replacing p with 0.5 in the formula for the sample size we get

$\bf n=6765.0625*0.5-6765.0625(0.5)^2=1691.27\approx 1,692$

rounded to the nearest integer.

ii)

When we do not have a proportion but a variable whose approximate standard deviation s is known, then the sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2s^2}{e^2}$

where

z = 2.241 is the critical value for a 95% confidence level (*) 

s = 7.5 is the estimated population standard deviation

e = 2 hours is the margin of error

so

$\bf n=\frac{z^2s^2}{e^2}=\frac{(2.241)^2(7.5)^2}{(2)^2}=70.62\approx 71$

(*)This is a point z such that the area under the Normal curve N(0,1) inside the interval [-z, z] equals 95% = 0.95

It can be obtained in Excel or OpenOffice Calc with

NORMSINV(0.9875)

5 0

4 years ago

Please Help. Find the value of x in the isosceles triangle shown below

ludmilkaskok [199]

Answer:

the answer is 6

Step-by-step explanation:

By pytagoras Theorem

hope its helpful

7 0

3 years ago