How do relational databases work mathematically?

Answers

Answer 1

Answer:

A relational database stores data in a series of tables so that the data models a mathematical theory of relations. The model allows for queries based on projection, selection, and join, among other operations, and connects the data in the tables by way of keys.

Answer 2

Answer:

Well, I guess in a formal sense you could call relational algebra a type of logic, which puts it into the realm of ‘math’, though I don’t think most mathematicians would look at it as being a very significant area, more ‘applied logic’ than anything else.

That being said, relational algebra DOES present some formalisms in the shape of relations, tuples, normalizations, and denormalization, etc. There is also a model of sequential operations and thus the underpinnings of the ACID database concept.

Since the overwhelming primary use of RA has been as a way to structure our ideas about SQL RDBMSes there isn’t really a lot of deep theory there. I don’t think anyone has really built any other models of RA beyond an RDBMS. There have been limited non-SQL RDBMS implementations, but AFAIK none of them are really actively maintained today.


Related Questions

In a survey of 600 students in a school. 150 student were found to be taking tea and 225 taking coffee, 100 were taking both tea and coffee Find how many Students were taking neither tea nor coffee​

Answers

Answer:

125

Step-by-step explanation:

600=150+225+100+X=475+X

600-475=125=X

X=125

Answer: 325 I believe!

Step-by-step explanation:

step below. Question 1 Hexagon AGHBGHCGHD GHEGHFGH is a reflected image of hexagon ABCDEF. The midpoints of the sides of hexagon ABCDEF are also shown. Drag the line of reflection, Għ until the image coincides with the preimage. At this location, if the preimage flips about the line of reflection, it will flip onto itself. In how many different positions can you place GHso the image reflects onto the preimage in this manner? Describe the different positions. Be sure to pass the line of reflection through both vertices and midpoints before answering.​

Answers

Answer:

Hexagon AGHBGHCGHDGHEGHFGH coincides with hexagon ABCDEF when GH passes through the midpoints of opposite sides; that is, it is a perpendicular bisector of the two sides. HexagonAGHBGHCGHDGHEGHFGH also coincides with hexagon ABCDEF when the line of reflection joins a pair of vertices opposite one another on the hexagon. There are three perpendicular bisectors and three pairs of opposite vertices. In all, there are six lines of reflection that will map the hexagon back onto itself.

Step-by-step explanation:

PROVE that x² + y² = r². you must explain your answer.

Answers

Fyucgghhhhh gghgeu. Hidings hec dog w

Answer:

Suppose f(x,y)=x2+y2

Let’s look at the partial derivatives of this function:

∂f∂x=2x

∂f∂y=2y

So apparently, at each (x,y) coordinate pair (black dots below), the gradient of f(x,y) is pointing in the same direction as the position vector itself (it is only twice as large). Knowing that an isocline f(x,y)=C (a curve on which f(x,y) is constant) must be perpendicular to the gradient of f(x,y) . This yields the following image:

This image depicts for two position vectors (black dots), the gradient (blue vectors), and the perpendicular direction in which f(x,y) is constant (red line fragments).

Doing this for many positions we see that this creates circles:

Therefore setting f(x,y)=C , yields a circle in the 2D plane, with radius r=C−−√ .

EDIT: again, thanks to Gilles Castel for the nice graphics!

A conic section (or simply conic) is a curve obtained as the intersection of the surface of a cone with a plane. The three types of conic section are thehyperbola, the parabola, and the ellipse. The circle is a special case of the ellipse, and is of sufficient interest in its own right that it was sometimes called a fourth type of conic section.

In the Cartesian coordinate system, the graph of a quadratic equation in two variables is always a conic section and all conic sections arise in this way. The most general equation is of the form

The conic sections described by this equation can be class

Consider a triangle with hypotenuse r and angle θ . As θ goes from 0 to 2π it traces out a circle.

The x and y coordinates are give by the basic trig equations:

x=rsin(θ)

y=rcos(θ)

Now if we compute x2+y2 we get

x2+y2

=r2sin2(θ)+r2cos2(θ)

=r2(sin2(θ)+cos2(θ))

=r2(1)

Hence x2+y2=r2 .

What is the answer for y?

Answers

the answer is in the picture

Yea the answer should so in the pic kinda simple

Will mark brainlest help me please​

Answers

Answer:

no le entiendo por qué estás en inglés

A study of homeowners in the 5th congressional district in Maryland found that their annual household incomes are normally distributed with a mean of $41,182 and a standard deviation of $11,990 (based on data from Nielsen Media Research). If an advertising campaign is to be targeted at those whose household incomes are in the top 20%, find the minimum income level for this target group.

Answers

Answer:

The minimum income level for this target group is of $51,253.6.

Step-by-step explanation:

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean of $41,182 and a standard deviation of $11,990

This means that [tex]\mu = 41182, \sigma = 11990[/tex]

Find the minimum income level for this target group.

The 100 - 20 = 80th percentile, which is X when Z has a p-value of 0.8, so X when Z = 0.84.

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]0.84 = \frac{X - 41182}{11990}[/tex]

[tex]X - 41182 = 0.84*11990[/tex]

[tex]X = 51253.6[/tex]

The minimum income level for this target group is of $51,253.6.

solve the logarithmic equation
[tex] log_{3} {x}^{2} - log_{3}(x + 6) = 1[/tex]

Answers

Answer:

Step-by-step explanation:

Using log(x) - log(y) = log (x/y)

logx^2 - log(x+6) = 1 is equal to:

log (x^2/(x+6)) = 1

Taking inverse base 3 log on both side:

x^2/(x+6) = 3

x^2 = 3x + 18

x^2 - 3x - 18 = 0

(x-6)(x+3) = 0

x = 6 or -3

Answer:

Step-by-step explanation:

1 = base 3log3

substitute

logx^2-log(x+6) = log3

logx^2 - log(x+6) - log3 = 0

log( (x^2/(x+6))/3 ) = 0

anti-log

x^2/3(x+6) = 1

x^2 = 3(x+6)

x^2-3x-18=0

x=6 n -3

anti-log base 3 on both sides:

if we have 765 toys and there are 3 people how many toys should we give to each man​

Answers

Answer:

255 is the answer

Step-by-step explanation:

Divide 765 by 3 and the answer will come .

Hope it will help u

A florist has to pay $7.50 each time a customer chooses a competitor for the delivery of flowers. Which expression
shows the amount that the florist earns if p people use a competitor for delivery, and the company makes $320.00
before any payment is made to their competitors?
0 320-7.500
0 320+ 7.500
7500-320
07500 + 320 help!

Answers

320-7.50p is the correct answer :D

Answer:

320-7.500

Step-by-step explanation:

Patel squeezed oranges so that his family could have fresh-squeezed juice for breakfast. He squeezed StartFraction 4 over 17 EndFraction cups from the first orange, StartFraction 3 over 10 EndFraction cups from the second orange, StartFraction 9 over 20 EndFraction cups from the third orange, StartFraction 3 over 11 EndFraction cups from the fourth orange, and StartFraction 7 over 15 EndFraction cups from the fifth orange. Patel estimates that he needs 3 cups of orange juice for his family. About how much more orange juice does he need to reach his estimate?

Answers

Answer:A

Step-by-step explanation:this is not true

Answer:

It A

Step-by-step explanation:

I had the question hope this helps!!!!!

AE = x=4.875, and EC = 13-4.875 = 8.125.
If I place point E at a distance of 4.875 units from A on AC-that is, E15.875, 1)-then the ratio of the segments into which e divides AC is equal to
the ratio of AD to DB.
Question 3
Place point that you found in Question 2 on AC. Draw a line passing through D and E, and measure and record the slopes of DE and BC.

Answers

Answer:

This is the answer for both Edmentum and Plato!

Step-by-step explanation:

Hope it helped

which of the gollowing cirxles lie completely within the third quadrant? Check all that apply​

Answers

Option B

Option C

These two circles lie completely within the third quadrant

Answered by GAUTHMATH

Solve the following simultaneous equations : 5m - 3n = 19; m - 6 = -7​

Answers

Answer:

m = -1

n= -8

Step-by-step explanation:

5m -3n = 19

m - 6 = -7

solve for m:

m = -7+6

m = -1

plug in m

5(-1) - 3n = 19

-5 - 3n = 19

-3n = 24

n = -8

Select three ratios equivalent to 4:34:34, colon, 3.Select three ratios equivalent to 4:34:34, colon, 3.

Answers

Answer:

A

C

D

Step-by-step explanation:

Select three ratios that are equivalent to 4:3.

Choose 3 answers:

(Choice A)

8:6

(Choice B)

9:12

(Choice C)

20:15

(Choice D)

32:24

(Choice E)

36:28

Ratio expresses the relationship between two or more numbers. It shows the frequency of the number of times that one value is contained within other value(s).

To determine which fractions are equivalent to 4:3 express the options in their lowest terms

option 1 - 8 : 6

To transform to the simplest form. divide the numbers by 2

4 : 3 this is equivalent

option 2 : 9 : 12

To transform to the simplest form. divide the numbers by 3

= 3 : 4 this is not equivalent

option 3 : 20:15

To transform to the simplest form. divide the numbers by 5

4 : 3 this is equivalent

option 4 : 32:24

To transform to the simplest form. divide the numbers by 8

4 : 3 this is equivalent

option 5 : 36:28

To transform to the simplest form. divide the numbers by 4

9 : 7 this is not equivalent

If the vertex of a parabola is (-4, 6) and another point on the curve is (-3, 14), what is the coefficient of the squared expression in the parabola's equation?

Answers

Answer:

[tex]y=a(x-h)^{2} +k[/tex]

[tex](x,y)=(-3,14)[/tex]

[tex](h,k)=(-4,6)[/tex]

[tex]14=a(-3-(-4))^{2})+6[/tex]

[tex]14=a(-3+4)^{2} +6[/tex]

[tex]14=a(1)^{2} +6,-6[/tex]

[tex]8=a[/tex]

[tex]ANSWER:8[/tex]

--------------------------

HOPE IT HELPS

HAVE A GREAT DAY!!

what is the measure of arc TUV

Answers

Answer:

196°

Step-by-step explanation:

A full circle has an arc measure of 360°.

360° - 164° = 196°

Answer: 196°

Evan, James, and Burt are fishing in a lake that has 200 fish. They are going to be fishing for three hours. What is the probability that they each will catch 3 fish?

Answers

Answer:

The probability that they each will catch 3 fish is 0.000063956

Step-by-step explanation:

The hyper geometric distribution is used to solve this as it has a population, a sample , number of successes  for both the population and sample.

Here

Population size= N =200

Sample size= n =9= (3*3)

Number of successes in population = k = 3 hours

Number of successes in sample = x= 3

Applying the hyper geometric distribution

P (x=3) = kCx *(N-k) C (n-x)/ N Cn

   = 3 C 3 * 197 C 6/ 200 C 9

    =0.000063956

The probability that they each will catch 3 fish is 0.000063956

Please help I don't understand this at all

Answers

Answer:

The answer is 48in

Step-by-step explanation:

I am pretty sure you add all the numbers together

You are given the exponential function g(x)=3^x. Which ootion below gives the formula for the new function h created by stretching g by a factor of 3 along the y-axis?

Answers

Answer:

h(x) = 3^(x + 1)

Step-by-step explanation:

The exponential function is;

g(x) = 3^(x)

Now, in transformation of exponential functions of say f(x) = b^(x), when the new function g(x) is created by stretching by a factor of say c along the y-axis, we have;

g(x) = c•b^(x)

In this question, we are told it is stretched by a factor of 3 along the y-axis.

Thus, new function h is;

h(x) = 3 × 3^(x)

Using law of indices, we have;

h(x) = 3^(x + 1)

Just Question B!
One of the numbers in the diagram is chosen at random, find the probability that the number is in set B, giving your answer as a decimal.
Gibing brainlist!

Answers

Answer:

0.4 or 0.40

Step-by-step explanation:

There are 10 total numbers. 4 of them are in set B.

So, 4/10 are in set B.

The probability is 0.4 because 4 divided by 10 is 0.4.

If AVB has a measure of 88° and VM is its angle bisector, what is the
measure of AVM?

A. 88°
B. 22°
C. 176°
D. 44

Answers

Answer:

B. 22°

Step-by-step explanation:

Angle bisector divides an angle into two equal angles.

Angle AVM = Angle MVM = Angle AVB / 2

Angle AVM = Angle AVB / 2

Angle AVM = 88 / 4

Angle AVM = 22°

Answer:

44

Step-by-step explanation:

If the numerator and the numerator of a fraction are subtracted 1, the resulting fraction is 2/3, if the resulting fraction is increased by 1, the resulting fraction is 3/4, determines the fraction.

Answers

Answer:

Simplify the expression.

Exact Form:

1 /2

Decimal Form:

0.5

Answer:

The Answer is

Fraction Form: 1/2

Decimal Form: 0.5

Percentage form: 50%

Step-by-step explanation:

I got the answer 1/2 by Adding 1 by 2/3, And then after that I got the answer 2/3 and with that I multiplyied it with 3/4 and I got 1/2

HELLPPPPPPPPPPPP i will give brainliest

Answers

Answer:

3[tex]\sqrt{2}[/tex]

Step-by-step explanation:

[tex]\sqrt{18}[/tex]

[tex]\sqrt{9}[/tex] [tex]\sqrt{2}[/tex]

3[tex]\sqrt{2}[/tex]

Given Q(x) = 7x − 3 and P(x) = 7x3 − 3x2 + 42x − 27, find P(x) Q(x) . (Divide using long division.)

Answers

Complete question:

Given Q(x) = 7x − 3 and P(x) = 7x3 − 3x2 + 42x − 27, find P(x) ÷ Q(x) . (Divide using long division.)

Answer:

[tex]\frac{7x^3 \ - \ 3x^2 \ + \ 42x \ - \ 27}{7x \ - \ 3} = \ \ x^2 + 6 \ \ \frac{-9}{7x \ - \ 3}[/tex]

The quotient = x²  + 6 and the remainder = - 9

Step-by-step explanation:

Given;

Q(x) = 7x − 3

P(x) = 7x³ − 3x² + 42x − 27

To divide P(x) by Q(x) using long division, we apply the following method;

                                 

                                      x²  + 6

                                  ---------------------------------

                  7x − 3   √ 7x³ − 3x² + 42x − 27

                               − (7x³ - 3x²)

                               -------------------------------------

                                               42x − 27

                                           − (42x  − 18)

                               ----------------------------------------

                                                       − 9

[tex]Therefore, \ \frac{7x^3 \ - \ 3x^2 \ + \ 42x \ - \ 27}{7x \ - \ 3} = \ \ x^2 + 6 \ \ \frac{-9}{7x \ - \ 3}[/tex]

The quotient = x²  + 6 and the remainder = - 9

                               

Someone please answer this

Answers

Answer:

(x - 1)(5x - 6)

Step-by-step explanation:

Given

5x² - 11x + 6

Consider the factors of the product of the coefficient of the x² term and the constant term (ac) which sum to give the coefficient of the x- term (b)

ac = 5 × 6 = 30 and b = - 11

The factors are - 5 and - 6

Use these factors to split the x- term

5x² - 5x - 6x + 6 ( factor the first/second and third/fourth terms )

= 5x(x - 1) - 6(x - 1) ← factor out (x - 1) from each term

= (x - 1)(5x - 6)

Please hurry

Consider the function represented by the table.
What is f(0)?
х
0
f(x)
6
7
0
5
O 4
O 5
O 6
4.
7

Answers

Answer:

[tex]f(0) = 6[/tex]

Step-by-step explanation:

Given

See attachment for table

Required

Determine [tex]f(0)[/tex]

From the table;

[tex]f(x) = 6[/tex] when [tex]x =0[/tex]

So:

[tex]f(0) = 6[/tex]

1/5 + 3/4 + 1/2
please helpppo asap

Answers

Answer:

29/20 or 1 9/20 or 1.45

Answer:

[tex]\frac{1}{5}+\frac{3}{4}+\frac{1}{2}[/tex]

lease common multiplier of 5,4,2 is 20

[tex]\frac{4}{20}+\frac{15}{20}+\frac{10}{20}[/tex]

[tex]Add\: 4+15+10= 29[/tex]

[tex]1/5+3/4+1/2=29/20[/tex]

[tex]Answer :\frac{29}{20}[/tex]

--------------------------

hope it helps

have a great day!!

find the value of the expressions 3x^3-2y^3-6x^2y^2+xy for x=2/3 and y=1/2

Answers

Hi!

[tex]3x^3-2y^3-6x^2y^2+xy=\\\\=3\cdot(\frac{2}{3})^3-2\cdot(\frac{1}{2})^3-6\cdot(\frac{2}{3})^2\cdot(\frac{1}{2})^2+\frac{2}{3}\cdot\frac{1}{2}=\\\\=3\cdot\frac{8}{27}-2\cdot\frac{1}{8}-6\cdot\frac{4}{9}\cdot\frac{1}{4}+\frac{1}{3}=\\\\=\frac{8}{9}-\frac{1}{4}-\frac{2}{3}+\frac{1}{3}=\frac{8}{9}-\frac{1}{4}-\frac{1}{3}=\frac{32}{36}-\frac{9}{36}-\frac{12}{36}=\boxed{\frac{11}{36}}[/tex]

You want to buy juices while shopping at ShopRite but are stuck between buying a bottle of apple juice and orange juice. The apple juice is 2 Liters and costs $3.00 while the orange juice is 3 Liters and costs $3.99. Which juice bottle is the better deal?

Answers

Answer:

Orange juice

Step-by-step explanation:

The bottle of apple juice costs 3 dollars for 2 liters, and the bottle of orange juice costs 3.99 dollars for 3 liters. To see which bottle has the better deal, we need to make the liters the same so we can compare them.

We can divide the 2 liters for 3 dollars ratio by 2 to get that 1 liter of apple juice costs 1.5 dollars, and we can divide the orange juice ratio by 3 to get that 1 liter of orange juice costs 1.33 dollars. We see that for 1 liter, orange juice is cheaper, so it is the better deal.


[tex]solve \: \\ \\ find \: the \: area \: of \: rectangle \: \\ \\ length = 11cm \\ \\ width = 9cm[/tex]

Answers

Area = l ×b

[tex]a = l \times b \\ a = 11 \times 9 \\ a = 99[/tex]

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why some fruits have 1 seed and some gruits have many seeds American history by judith ortiz cofer What were yourthoughts aboutElena and heremotions at the endof the story?ComprWhestory A wooden board 27 ft long is cut into two pieces so that the longer piece is 8times as long as the shorter piece. Find the lengths of the two pieces. Need help~ What is the measure of arc sty in the circle O below Directions read each item carefully. Write the letter of the correct answer. 1. A group of pupils is planning to have their dance practice on the gym after class. What is the first thing to be considered in order for them to avoid accident? A. Make sure that the place is safe for dancing. B. Have your practice using your school uniform C. Continue practicing even if the place is not clean. D. Continue practicing without the permission of the teacher 2. Jessie is still suffering from his mild sprain but still continued to join the dance competition. Which of the following is the safety precaution that he didn't consider? A. Inexperience B. Poor Posture C. Hazardous environment D. Failure to rest an injury 3. What is the first thing to do before you start any physical or dance activity? A. Do a warm-up exercise. B. Proceed even if you feel pain C. Wear uncomfortable clothes. D. Start dancing without the instruction of the teacher. 4. Which of the following statements is true? A. People dance just for fun. B. Dancing can make us feel unhealthy. C. Following safety precautions increases the chances of accidents and injuries. D. We should always be guided by safety precautions even without the presence of our teachers. 5. Vina finds it hard to cope up with basic steps being taught by their teacher because it is her first time to dance. What is the hazard that affects her performance? A. Overtraining B. Poor Fitness C. Inexperience D. Hazardous Environment when is the population of a country counted, yearly, annually, daily. 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You want to save electrical energy by dropping the bulb from a height great enough so that the kinetic energy of the bulb when it reaches the floor will be the same as the energy it took to keep the bulb on for 2.0 hours. From what height should you drop the bulb, assuming no air resistance and constant g? What was most likely the authors immediate purpose in writing "What to the Slave is the Fourth of July? Wine goes bad soon after opening because the ethanol dissolved in it reacts with oxygen gas to form water and aqueous acetic acid , the main ingredient in vinegar. Calculate the moles of acetic acid produced by the reaction of of ethanol. Be sure your answer has a unit symbol, if necessary, and round it to significant digits. Describe how first Aid will be given a lictim under the following accidents at work Shop. Chemical barns Electric shock Fire burns Atlanta's population is growing at a rate of 2.9% per year while Detroit's population is declining at 1.1% per year. Describe what this means. PLSSS HELPPP!!!!! in the outsiders which line best supports the authors message that some things in life are out of people control?