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Evgen [1.6K]
3 years ago
5

1:X = X:81 what number can replace X?

Mathematics
1 answer:
anygoal [31]3 years ago
7 0

Multiply 1/x = x/81 by 81x and you get

... 81 = x²

Taking the square root gives

... x = ±9

Either 9 or -9 can replace X to make the proportion statement true.

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Current rules for telephone area codes allow the use of digits​ 2-9 for the first​ digit, and​ 0-9 for the second and third​ dig
Anna35 [415]

Using the fundamental counting theorem, we have that:

  • 648 different area codes are possible with this rule.
  • There are 6,480,000,000 possible 10-digit phone numbers.
  • The amount of possible phone numbers is greater than 400,000,000, thus, there are enough possible phone numbers.

The fundamental counting principle states that if there are p ways to do a thing, and q ways to do another thing, and these two things are independent, there are ways to do both things.

For the area code:

  • 8 options for the first digit.
  • 9 options for the second and third.

Thus:

8 \times 9 \times 9 = 648

648 different area codes are possible with this rule.

For the number of 10-digit phone numbers:

  • 7 digits, each with 10 options.
  • 648 different area codes.

Then

648 \times 10^7 = 6,480,000,000


There are 6,480,000,000 possible 10-digit phone numbers.

The amount of possible phone numbers is greater than 400,000,000, thus, there are enough possible phone numbers.

A similar problem is given at brainly.com/question/24067651

5 0
2 years ago
Write a proportion you could use to convert 2.5 gallons to quarts.
marusya05 [52]
We know there are 4 quarts in a gallon, so how many quarts in 2.5 gallons anyway?

\bf \begin{array}{ccll}
quarts&gallons\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
4&1\\
x&2.5
\end{array}\implies \cfrac{4}{x}=\cfrac{1}{2.5}\implies \cfrac{4\cdot 2.5}{1}=x
5 0
3 years ago
The quantity of four minus one all raised to the five-minus- two power
leva [86]

Answer:

(4-1)^5-2

Step-by-step explanation:

The quantity means parenthesis, around four minus one, (closed quantity), all raised to the power (exponent) five minus 2

3 0
3 years ago
Read 2 more answers
OK, I REALLY NEED ALL OF THIS DONE SOON!
Rudik [331]

Answer: 1. 140 times

Step-by-step explanation:

4 0
3 years ago
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mr and mrs gracia took their three children to see a matinee on saturday. they spent a total of 55.50, which included 29.95 at t
andrezito [222]

First, you would subtract 29.95 from 55.50, and you get 25.55. because 5 people went, and the cost for each was the same, you would divide 25.55 by five, and get $5.11 per person.
3 0
3 years ago
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