Exercise 2.4.2: Proving statements about rational numbers with direct proofs. About Prove each of the following statements using a direct proof. (a) The product of two rational numbers is a rational number. Solution (b) The quotient of a rational number and a non-zero rational number is a rational number. Solution (c) If x and y are rational numbers then is also a rational number.

Answers

Answer 1

Answer:

See Explanation

Step-by-step explanation:

(a) Proof: Product of two rational numbers

Using direct proofs.

Let the two rational numbers be A and B.

Such that:

[tex]A = \frac{1}{2}[/tex]

[tex]B = \frac{2}{3}[/tex]

The product:

[tex]A * B = \frac{1}{2} * \frac{2}{3}[/tex]

[tex]A * B = \frac{1}{1} * \frac{1}{3}[/tex]

[tex]A * B = 1 * \frac{1}{3}[/tex]

[tex]A * B = \frac{1}{3}[/tex]

Proved, because 1/3 is rational

(b) Proof: Quotient of a rational number and a non-zero rational number

Using direct proofs.

Let the two rational numbers be A and B.

Such that:

[tex]A = \frac{1}{2}[/tex]

[tex]B = \frac{2}{3}[/tex]

The quotient:

[tex]A / B = \frac{1}{2} / \frac{2}{3}[/tex]

Express as product

[tex]A / B = \frac{1}{2} / \frac{3}{2}[/tex]

[tex]A / B = \frac{1*3}{2*2}[/tex]

[tex]A / B = \frac{3}{4}[/tex]

Proved, because 3/4 is rational

(c) x + y is rational (missing from the question)

Using direct proofs.

Let x and y be

Such that:

[tex]x = \frac{1}{2}[/tex]

[tex]y = \frac{2}{3}[/tex]

The sum:

[tex]x + y = \frac{1}{2} + \frac{2}{3}[/tex]

Take LCM

[tex]x + y = \frac{3+4}{6}[/tex]

[tex]x + y = \frac{7}{6}[/tex]

Proved, because 7/6 is rational

The above proof works for all values of A, B, x and y; as long as they are rational values


Related Questions

Help ? PLEASE HURRY !

Answers

Answer:

Step-by-step explanation:

Sine of U = 8/17

opposite /hypotensue


10 points
Michael surveyed every tenth child who entered a state fair about the number of rides they planned
on riding. What is the population for Michael's sample?
A. every tenth child who entered the state fair
B. all the people at the state fair
C. all the children at the state fair
D. every adult with children at the state fair
A
OD

Answers

Answer:

C

Step-by-step explanation:

All children at the state fair

A.
the question says every tenth child. not all the children.

B. Translate each statement to an equation using k as the constant of variation.
1. m varies directly to a.
2. p varies inversely as q.
3. r varies directly as s and inversely as t.
4. z varies jointly as e and f.
5. F varies directly as the square of t.
6. The distance (d) traveled by a car varies jointly as the rate (r) and the time (t) of travel.
7. The air pressure (P) in inversely proportional to the altitude (h).
8. The amount of water pressure (P) in a closed container varies directly as the volume (V) of the
water.
9. The distance (d) of a falling body varies directly as the square of the time (t) traveled.
1
10. The stiffness (s) of a beam varies jointly as its breadth (b) and depth (d) and inversely as the
square
of its length (L).
2​

Answers

Answer:

See Explanation

Step-by-step explanation:

To do this, we will make use of the following rules:

Direct Variation: [tex]a\ \alpha\ b[/tex] => [tex]a = kb[/tex]

Inverse Variation: [tex]a\ \alpha\ \frac{1}{b}[/tex] ==> [tex]a = k/b[/tex]

Joint Variation: [tex]a\ \alpha\ bc[/tex] ==> [tex]a= kbc[/tex]

Direct, then inverse variation: [tex]a\ \alpha\ b\ \alpha\ \frac{1}{c}[/tex] ==> [tex]a= kb/c[/tex]

Having highlighted the rules, the solution is as follows:

1. m varies directly to a

[tex]m\ \alpha\ a[/tex]

[tex]m =ka[/tex]

2. p varies inversely as q.

[tex]p\ \alpha\ \frac{1}{q}[/tex]

[tex]p\ = k\frac{1}{q}[/tex]

3. [tex]r\ varies[/tex] directly as s and inversely as t.

[tex]r\ \alpha\ s\ \alpha\ \frac{1}{t}[/tex]

[tex]r = k\frac{s}{t}[/tex]

4. z varies jointly as [tex]e\ and\ f.[/tex]

[tex]z\ \alpha \ ef[/tex]

[tex]z = kef[/tex]

5. F varies directly as the [tex]square\ of\ t.[/tex]

[tex]F\ \alpha\ t^2[/tex]

[tex]F = kt^2[/tex]

6. d varies jointly r and t

[tex]d\ \alpha\ rt[/tex]

[tex]d = krt[/tex]

7. P is inversely proportional to h.

[tex]P\ \alpha\ \frac{1}{h}[/tex]

[tex]P= \frac{k}{h}[/tex]

8. P varies directly as V

[tex]P\ \alpha\ V[/tex]

[tex]P=kV[/tex]

9. d varies directly as the square of  t

[tex]d\ \alpha\ t^2[/tex]

[tex]d = kt^2[/tex]

10. s varies jointly as  b and d and inversely as the  square L

[tex]s\ \alpha\ bd\ \alpha\ \frac{1}{L^2}[/tex]

[tex]s = k\frac{bd}{L^2}[/tex]

The translation of each statement to an equation using k as the constant of variation is

1. m varies directly to a.

m = k × a

m = ka

2. p varies inversely as q

p = k / q

3. r varies directly as s and inversely as t

r = (k × s) / t

r = ks / t

4. z varies jointly as e and f.

z = k × e × f

z = kef

5. F varies directly as the square of t.

F = k × t²

F = kt²

6. The distance (d) traveled by a car varies jointly as the rate (r) and the time (t) of travel.

d = k × r × t

d = krt

7. The air pressure (P) in inversely proportional to the altitude (h).

P = k / h

8. The amount of water pressure (P) in a closed container varies directly as the volume (V) of the

water.

P = k × V

P = kV

9. The distance (d) of a falling body varies directly as the square of the time (t) traveled.

d = k × t²

d = kt²

10. The stiffness (s) of a beam varies jointly as its breadth (b) and depth (d) and inversely as the

square of its length (L).

s = (k × b × d) / L²

s = kbd / L²

Read more:

https://brainly.com/question/472621

What is the value of z?
62
Enter your answer in the box.
95

Answers

Answer:

Value of z = 23°

Step-by-step explanation:

Given:

∠1 = 62°

∠2 = 95°

∠3 = z°

Find:

Value of z

Computation:

Using angle sum property

∠1 + ∠2 + ∠3 = 180°

62 + 95 + z° = 180

Value of z = 23°

If the diameter of the circle is 6 cm, find its circumference. [Use 3.14 for π

Answers

The circumference of the circle with a diameter of 6 cm will be 18.84 cm.

What is the circumference of a circle?

It is the close curve of an equidistant point drawn from the center. The radius of a circle is the distance between the center and the circumference.

Let d be the diameter of the circle. The circumference of the circle will be given as,

C = πd units

The diameter of the circle is 6 cm. Then the circumference is given as,

C = π x 6

C = 3.14 x 6

C = 18.84 cm

The circumference of the circle with a diameter of 6 cm will be 18.84 cm.

More about the circumference of a circle link is given below.

https://brainly.com/question/27177006

#SPJ1

Please help I need due rn

Answers

Answer:

4 3/12

Step-by-step explanation:

= 4.25 = 4 1/4 = 4 3/12

The personnel department of Anna's Wholesale Bakery is preparing annual
reports on employee benefits. Hannah Prosser's gross annual salary is $29,500.
Her benefits total $8,673.25. Hannah's total annual benefits are what percent of
her annual salary?

Answers

Answer:

$32,277.80

Step-by-step explanation:

How can 38 over 6 be expressed as a decimal?
A. 5.1 with bar over 1
B. 6.1 with bar over 1
C. 6.3 with bar over 3

Answers

Answer:

B

Step-by-step explanation:

C its C hopes this helps

A bacteria with an initial size of 180in2 grows by 27% every minute. What will the size of the bacteria be after 8hours

Answers

Answer:

The size of the bacteria after 8 hours will be of [tex]1.2 \times 10^{52}[/tex] squared inches.

Step-by-step explanation:

Exponential function:

An exponential function has the following format:

[tex]F(t) = F(0)(1+r)^{t}[/tex]

In which F(0) is the initial value and F is the growth rate.

A bacteria with an initial size of 180in2 grows by 27% every minute.

This means that [tex]F(0) = 180, r = 0.27[/tex]. So

[tex]F(t) = F(0)(1+r)^{t}[/tex]

[tex]F(t) = 180(1+0.27)^{t}[/tex]

[tex]F(t) = 180(1.27)^{t}[/tex]

In which t is measured in minutes,

What will the size of the bacteria be after 8hours

8 hours has 8*60 = 480 minutes, so this is F(480).

[tex]F(480) = 180(1.27)^{480} = 1.2 \times 10^{52}[/tex]

The size of the bacteria after 8 hours will be of [tex]1.2 \times 10^{52}[/tex] squared inches.

solve for the indicated variable in the literal equation ​

Answers

Answer:

[tex]x = \frac{y}{3} - \frac{5}{3}[/tex]

Step-by-step explanation:

Given

[tex]y = 5 + 3x[/tex]

Required

Solve for x

Subtract 5 from both sides

[tex]y-5 = 5 -5+ 3x[/tex]

[tex]y-5 = 3x[/tex]

Divide through by 3

[tex]\frac{y}{3} - \frac{5}{3} = x[/tex]

[tex]x = \frac{y}{3} - \frac{5}{3}[/tex]

Find the volume of this right rectangular prism. [Type your answer as a number.]
1

Answers

Answer:

200 cm3

Step-by-step explanation:

Multiply 10x4x5=200

A hotel manager is adding a tile border around the​ hotel's rectangular pool. let n represent the width of the​ pool, in feet. the length is 3 more than 3 times the​ width, as shown. Write two expressions that represent the perimeter of the pool.

Answers

Answer:

[tex]2(4n+3)[/tex]

[tex]8n+6[/tex]

Step-by-step explanation:

We are given that

Let n represent the width of pool

Length of pool=[tex]3n+3[/tex]

We have to find two expression which represent the perimeter of the pool.

We know that

Perimeter of rectangle=[tex]2(l+b)[/tex]

Where l=Length of rectangle

b=Width of rectangle

Using the formula

Perimeter of pool=[tex]2(n+3n+3)[/tex]

Perimeter of pool=[tex]2(4n+3)[/tex]

Perimeter of pool=[tex]8n+6[/tex]

Hence,  two expressions that represent the perimeter of the pool is given by

[tex]2(4n+3)[/tex]

[tex]8n+6[/tex]

madison paid $53.58 in sales tax on her books. the sales tax was 8.6% of the cost of the books. how much did madison's books cost before tax?

Answers

Answer:

$48.98

Step-by-step explanation:

first move the decimal of your percent 2 places

8.6% = .086

then multiply by 53.58

.086 × 53 58= 4.60

subtract 4.60 from 53.58

53.58 - 4.60= 48.98

Multiply (X - 4) squared

Answers

Answer:

it's the fourth answer

Step-by-step explanation:

(X-4) (X-4)

[tex]x^{2}[/tex]-4x-4x+16

[tex]x^{2}[/tex]-8x+16

The expression is x² + 8x + 16. The correct answer is a) x² + 8x + 16.

To multiply (x - 4)², we can use the concept of expanding a binomial squared. The formula for expanding a binomial squared is:

(a - b)² = a² - 2ab + b²

In this case, a = x and b = 4. Substituting these values into the formula, we have:

(x - 4)² = x² - 2(x)(4) + 4²

= x² - 8x + 16

Therefore, the correct option is a) x² + 8x + 16.

To know more about binomial squared:

https://brainly.com/question/29142274


#SPJ6

find the positive zero of the function f(x)=x^(2)-5x-7 and round two decimal places

Answers

Answer:

6.14

Step-by-step explanation:

Given the function f(x)=x^(2)-5x-7, when f(x) = 0

x^(2)-5x-7 = 0

Using the general formula

x = 5±√5²-4(-7)/21(1)

x= 5±√25+28/2

x = 5±√53/2

x = -5±7.28/2

x = 5+7.28/2 and 5-7.28/2

x = 12.28/2 and -2.28/2

x = 6.14 and -1.14

Hence the positive zero is 6.14

PLS ANSWER IN 5 MINS
I WILL MARK BRAINLIEST
THE QUESTION IS IN THE PICTURE I ATTACHED

Answers

Answer:

[tex]\frac{19}{14}x + \frac{97}{56}[/tex] =

^^^hope this helps! :)

simplify (-4/5)^9/(-4/5)^10​

Answers

Answer:

[tex]-\frac{5}{4}[/tex]

Step-by-step explanation:

We are given two fractions and are asked to simplify it.

So

[tex](-\frac{4}{5} )^9 / (-\frac{4}{5} )^{10}[/tex]

We can follow the exponent rule of subtracting them since both fractions are the same value.

[tex](-\frac{4}{5} )^{9-10}[/tex]

[tex](-\frac{4}{5} )^{-1}[/tex]

Now do the negative exponent rule :

[tex]\frac{1}{-\frac{4}{5} }[/tex]

Move the negative in between the fraction :

[tex]-\frac{1}{\frac{4}{5} }[/tex]

And apply the fraction switcharoo :

[tex]\frac{5}{4}[/tex]

A data scientist studying a manufacturing process classifies each item produced by the process as either Poor, Acceptable, or Excellent. Assume that the classes of different items are independent of each other and that each item falls into the classes according to the following probabilities:

Poor Acceptable Excellent
0.25 0.6 0.15

The data scientist receives three items produced by the manufacturing process.
Find the chance that:
a. all of items are Acceptable
b. none of the items is Acceptable
c. at least one of the items is Excellent
d. not all of the items are Excellent
e. there is one item of each class

Answers

Answer:

0.214 ; 0.064 ; 0.3859 ; 0.9966 ; 0.135

Step-by-step explanation:

Given the distribution :

Poor ___ Acceptable ____ Excellent

0.25 _____ 0.6 _________ 0.15

The data scientist receives three items produced by the manufacturing process.

Find the chance that:

a. all of items are Acceptable

0.6 * 0.6 * 0.6 = 0.6^3 = 0.214

b. none of the items is Acceptable

P(not acceptable) = 1 - p(acceptable) = 1 - 0.6 = 0.4

0.4 * 0.4 * 0.4 = 0.4^3 = 0.064

c. at least one of the items is Excellent

P(atleast one) = 1 - P(none)

P(not excellent) = 1 - 0.15 = 0.85

P(none is excellent) = 0.85^3 = 0.614125

Hence,

P(atleast one is excellent) = 1 - 0.614125 = 0.3859

d. not all of the items are Excellent

P(not all) = 1 - p(All)

P(all excellent) = 0.15^3 = 0.003375

P(not all are excellent) = 1 - 0.003375 = 0.9966

e. there is one item of each class:

P(poor) * p(acceptable) * p(excellent) * (number of classes)!

0.25 * 0.6 * 0.15 * 3!

= 0.135

Solve the equation 15=7+b

Answers

Answer:

[tex]b=8[/tex]

Can i have brain plz

HURRY , Write the coordinates of the vertices after a reflection across the line x = 5. (will give brainiest)

Answers

Answer:

U: (5,9)

W: (7,9)

V: (6,10)

T: (6,7)

Step-by-step explanation:

What’s the answer? Please help

Answers

11 Because 2(3) means 2x3 which is 6 and then you add 6 to 5 which gives you 11

HELP ME PLEASEEEEEEEEEE

Answers

Answer: B

Step-by-step explanation: A=πr2

The formula for calculating the area of a circle is A = π​r​2 where pi (π) equals 3.14 and the radius (​r​) is half the diameter.

You must times 5 by 5 because of exponents and then times it by pie

5 times 5 = 25

25 times pie is 78.5

solve triangle. round to the nearest tenth​

Answers

Answer:

37.5 ( i didn't round cause the answer looked simple already)

Step-by-step explanation:

formula for triangle is base x height divided by 1/2

Base(5) x Height(15) = 75 now divide by 1/2

75 divided by 1/2 = 37.5

(Could i have brainliest if i'm right?)

Steve is turning half of his backyard into a chicken pen. His backyard is a 24 meter by 45 m rectangle. He wants to put a chicken wire fence that stretches diagonally from one corner to the opposite corner.

How many meters of fencing will Steve need?

Answers

Answer: 12 is the awnser

Step-by-step explanation: simple math.

Fill in the blanks: what numbers will make the equation true? 4 * ___ / 6 + ___ = 11 *

Answers

One of the possible answers could be 4*0/6+11=11 because if 0 is put into the first part of the equation, that will make it equal to 0. Then, if you add 11 to 0 it will give you the number equal to 11. There are other possible answers but this is just the first one that I thought of. Hope it helped!

I need help with this

Answers

Answer:

76

Step-by-step explanation:

We know that the two angles must add up to 90 which means that

12+x-2=90

solve for x

14+x=90

x= 76

last week Kellie ran 28 miles. this week she ran 32. what was the percent change in number of miles she ran

Answers

4/28= 1/7 = 14.3%......

Point Q is graft at (N, -2). The distance from P to Q is equal to the distance from P point R. What is the distance from point P to point Q? What is the value of N? Explain how you determine the distance from point B to point Q, and the value in.

Answers

Answer:

ndndnjxhdhfjhfjdirudjfjutt

The radius of a sphere is 18 feet. What is the surface area of the sphere? Express the answer in terms of pi. Recall the formula SA = 4pi 2

Answers

Answer: 1296π

Step-by-step explanation:

To find the surface are if a square, we have to use the formula:

= 4πr²

= 4 × π × 18²

= 4 × π × 324

= 1296π

Therefore, the surface area of the sphere is 1296π

Answer:

C

Step-by-step explanation:

I did the test right

write ⅔of 4 as a fraction

Answers

Answer:

2/3 of 4=8/3or 2 2/3 is your answer

Answer:

I have 2.66667 As a fraction it is 4/1

Step-by-step explanation:

I'm not completely sure I'm new to this :|

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