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boyakko [2]
3 years ago
15

If x-y=9,x²+y²=27,then xy=?​

Mathematics
1 answer:
Tresset [83]3 years ago
5 0

Answer:

xy = - 27

Step-by-step explanation:

Note that

(x - y)² = x² - 2xy + y² ← substitute given values, that is

9² = 27 - 2xy

81 = 27 - 2xy ( subtract 27 from both sides )

54 = - 2xy (divide both sides by - 2 )

- 27 = xy

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6th grade math I mark as brainliest
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Answer:

False

Step-by-step explanation:

2*2*2*2 is the correct answer

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3 years ago
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it takes him 6 hours through 480 pages today he's going to read for 5 hours how many pages will be read fill out the table below
ad-work [718]
Its 400 pages becasue he reads 80 pages per hour
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3 years ago
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Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.3. (Round your ans
Maurinko [17]

Answer:

0.0039 is the probability that the sample mean hardness for a random sample of 12 pins is at least 51.

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 50

Standard Deviation, σ = 1.3

Sample size, n = 12

We are given that the distribution of hardness of pins is a bell shaped distribution that is a normal distribution.

Formula:

z_{score} = \displaystyle\frac{x-\mu}{\sigma}

Standard error due to sampling =

=\dfrac{\sigma}{\sqrt{n}} = \dfrac{1.3}{\sqrt{12}} = 0.3753

P(sample mean hardness for a random sample of 12 pins is at least 51)

P( x \geq 51) = P( z \geq \displaystyle\frac{51 - 50}{0.3753}) = P(z \geq 2.6645)

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Calculation the value from standard normal z table, we have,  

P(x \geq 51) = 1 - 0.9961= 0.0039

0.0039 is the probability that the sample mean hardness for a random sample of 12 pins is at least 51.

3 0
3 years ago
Problem is in the attached image. Thanks in advance!
lutik1710 [3]

Answer: it will take 2.5 hours for both people to meet after person B leaves.

Step-by-step explanation:

The distance between the house of person A and his cousin's house is 234 miles.

At the point where they meet, they would have travelled 234 miles.

Person A travelled at an average speed of 44 miles per hour.

Let t represent the time spent by Person A in travelling from his house to the point where they meet.

Distance = speed × time

Distance covered by person A would be

44 × t = 44t

One and half hours later, person B leaves his house to visit person A, travelling at an average speed of 62 miles per hour. This means that total time spent by person B in travelling to the point where they meet is (t - 0.5) hours. Distance covered would be

62(t - 0.5) = 62t - 31

Since the total distance covered is 234 miles, then

44t + 62t - 31 = 234

106t = 234 + 31 = 265

t = 265/106 = 2.5 hours

3 0
3 years ago
Solve <br><br> 9x-14-2x=5(2x-6)
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3 years ago
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