A dryer and washer cost $936 combined the washer cost $86 more than the dryer what is the cost of the dryer

What is the sum of the first 70 consecutive odd numbers? Explain.

expeople1 [14]

The sum of the first n odd numbers is n squared! So, the short answer is that the sum of the first 70 odd numbers is 70 squared, i.e. 4900.

Allow me to prove the result: odd numbers come in the form 2n-1, because 2n is always even, and the number immediately before an even number is always odd.

So, if we sum the first N odd numbers, we have

$\displaystyle \sum_{i=1}^N 2i-1 = 2\sum_{i=1}^N i - \sum_{i=1}^N 1$

The first sum is the sum of all integers from 1 to N, which is N(N+1)/2. We want twice this sum, so we have

$\displaystyle 2\sum_{i=1}^N i = 2\cdot\dfrac{N(N+1)}{2}=N(N+1)$

The second sum is simply the sum of N ones:

$\underbrace{1+1+1\ldots+1}_{N\text{ times}}=N$

So, the final result is

$\displaystyle \sum_{i=1}^N 2i-1 = 2\sum_{i=1}^N i - \sum_{i=1}^N 1 = N(N+1)-N = N^2+N-N = N^2$

which ends the proof.

5 0

2 years ago

Math on khan academy

IRINA_888 [86]

The answer is b I believe

5 0

2 years ago

Y ( x + w ) = c ( x + z )

ycow [4]

The formula for x in terms of other terms in the equation is; x = (cz-yw)/(y-c).

<h3>What is the formular for x in term of other terms in the equation?</h3>

According to the task content, it follows that the variable X is to be made the subject of the formula;

Hence, it follows that;

y ( x + w ) = c ( x + z )

yx +yw = cx +cz

x(y-c) = (cz-yw)

x = (cz-yw)/(y-c)

Remarks: The complete question requires that x be made the subject of the formula.

Read more on subject of formula;

brainly.com/question/11000305

#SPJ1

7 0

2 years ago

A study was done that looked at how much red meat people consumed and how long they lived. The correlation r was found to be 0.9

AVprozaik [17]

Answer:

False

Step-by-step explanation:

Since the correlation r was found to be 0.98 (a value closer to 1).

Let X =how much red meat people consumed

let Y = how long they lived.

where the x-values are the values of the deviations of co-ordinates X from Xₙ, their mean value and the y-values are the values of the deviations of co-ordinates Y from Yₙ, their mean value.

That is, x=(X−Xₙ) and y=(Y−Yₙ).

The results of this determination give values of r lying between +1 and −1, where;

+1 indicates perfect direct correlation,

−1 indicates perfect inverse correlation and

0 indicates that no correlation exists.

Between these values, the smaller the value of r, the less is the amount of correlation which exists.

Generally, values of r in the ranges 0.7 to 1 and −0.7 to −1 show that a fair amount of correlation exists.

therefore, it can be seen that there is a perfect relationship between the quantity eaten and how long the person live

But, the correlation does not consider those that does not consume meat, and it is very hard to determined the answer to the question.

the answer is false because there are other reasons that determined longevity of life apart from meat consumption.

3 0

3 years ago

Ruby wanted to get an iPod for 350$ she already had 52$ saved and if she worked for 8 hours a week for 9$ an hour how many weeks

WARRIOR [948]

Answer:

I believe that the answer is 4.13 weeks

Step-by-step explanation:

Since she already has $52 you can automatically start by doing:

$350 - $52 = $298

Since she works 8 hours a week and earns $9 per hour:

8 hours x $9 = $72

Then, take $298 ÷ $72 = 4.13 or about 4 weeks

I divide 298 by 72 because $72 is how much she will earn per week, and by dividing this number by the total amount that she has left to pay narrows it down to about how long she has to save for.

Hope this helps!!

4 0

2 years ago