Find the supremum and infimum of each of the following sets of real numbers
S = {3x 2 − 10x + 3 < 0}​

Answers

Answer 1

Answer:

[tex]\sup(S) = 3[/tex].

[tex]\displaystyle \inf(S) = \frac{1}{3}[/tex].

Step-by-step explanation:

When factored, [tex]3\,x^{2} - 10\, x + 3[/tex] is equivalent to [tex](3\, x - 1)\, (x - 3)[/tex].

[tex]3\, x^{2} - 10\, x + 3 < 0[/tex] whenever [tex]\displaystyle x \in \left(\frac{1}{3},\, 3\right)[/tex].

Typically, the supremum and infimum of open intervals are the two endpoints. In this question, [tex]\sup(S) = 3[/tex] whereas [tex]\displaystyle \inf(S) = \frac{1}{3}[/tex].

Below is a proof of the claim that [tex]\sup(S) = 3[/tex]. The proof for [tex]\displaystyle \inf(S) = \frac{1}{3}[/tex] is similar.

In simple words, the supremum of a set is the smallest upper bound of that set. (An upper bound of a set is greater than any element of the set.)

It is easy to see that [tex]3[/tex] is an upper bound of [tex]S[/tex]:

For any [tex]x > 3[/tex], [tex]3\,x^{2} - 10\, x + 3 > 0[/tex]. Hence, any number that's greater than [tex]3\![/tex] could not be a member [tex]S[/tex]. Conversely, [tex]3[/tex] would be greater than all elements of [tex]S\![/tex] and would thus be an upper bound of this set.

To see that [tex]3[/tex] is the smallest upper bound of [tex]S[/tex], assume by contradiction that there exists some [tex]\epsilon > 0[/tex] for which [tex](3 - \epsilon)[/tex] (which is smaller than [tex]3\![/tex]) is also an upper bound of [tex]S\![/tex].

The next step is to show that [tex](3 - \epsilon)[/tex] could not be a lower bound of [tex]S[/tex].

There are two situations to consider:

The value of [tex]\epsilon[/tex] might be very large, such that [tex](3 - \epsilon)[/tex] is smaller than all elements of [tex]S[/tex].Otherwise, the value of [tex]\epsilon[/tex] ensures that [tex](3 - \epsilon) \in S[/tex].

Either way, it would be necessary to find (or construct) an element [tex]z[/tex] of [tex]S[/tex] such that [tex]z > 3 - \epsilon[/tex].

For the first situation, it would be necessary that [tex]\displaystyle 3 - \epsilon \le \frac{1}{3}[/tex], such that [tex]\displaystyle \epsilon \ge \frac{8}{3}[/tex]. Let [tex]z := 1[/tex] (or any other number between [tex](1/3)[/tex] and [tex]3[/tex].)

Apparently [tex]\displaystyle 1 > \frac{1}{3} \ge (3 - \epsilon)[/tex]. At the same time, [tex]1 \in S[/tex]. Hence, [tex](3 - \epsilon)[/tex] would not be an upper bound of [tex]S[/tex] when [tex]\displaystyle \epsilon \ge \frac{8}{3}[/tex].

With the first situation [tex]\displaystyle \epsilon \ge \frac{8}{3}[/tex] accounted for, the second situation may assume that [tex]\displaystyle 0 < \epsilon < \frac{8}{3}[/tex].

Claim that  [tex]\displaystyle z:= \left(3 - \frac{\epsilon}{2}\right)[/tex] (which is strictly greater than [tex](3 - \epsilon)[/tex]) is also an element of [tex]S[/tex].

To verify that [tex]z \in S[/tex], set [tex]x := z[/tex] and evaluate the expression: [tex]\begin{aligned} & 3\, z^{2} - 10\, z + 3 \\ =\; & 3\, \left(3 - \frac{\epsilon}{2}\right)^{2} - 10\, \left(3 - \frac{\epsilon}{2}\right) + 3 \\ = \; &3\, \left(9 - 3\, \epsilon - \frac{\epsilon^{2}}{4}\right) - 30 + 5\, \epsilon + 3 \\ =\; & 27 - 9\, \epsilon - \frac{3\, \epsilon^{2}}{4} - 30 + 5\, \epsilon + 3 \\ =\; & \frac{3}{4}\, \left(\epsilon\left(\frac{16}{3} - \epsilon\right)\right)\end{aligned}[/tex].This expression is smaller than [tex]0[/tex] whenever [tex]\displaystyle 0 < \epsilon < \frac{16}{3}[/tex]. The assumption for this situation [tex]\displaystyle 0 < \epsilon < \frac{8}{3}[/tex] ensures that [tex]\displaystyle 0 < \epsilon < \frac{16}{3}\![/tex] is indeed satisfied. Hence, [tex]\displaystyle 3\, z^{2} - 10\, z + 3 < 0[/tex], such that [tex]z \in S[/tex].At the same time, [tex]z > (3 - \epsilon)[/tex]. Hence, [tex](3 - \epsilon)[/tex] would not be an upper bound of [tex]S[/tex].

Either way, [tex](3 - \epsilon)[/tex] would not be an upper bound of [tex]S[/tex]. Contradiction.

Hence, [tex]3[/tex] is indeed the smallest upper bound of [tex]S[/tex]. By definition, [tex]\sup(S) = 3[/tex].

The proof for [tex]\displaystyle \inf(S) = \frac{1}{3}[/tex] is similar and is omitted because of the character limit.


Related Questions

James is putting a fence around his square yard. The area of his yard is 100 square feet. How much fencing does James need in total to go around all
four sides of his yard?
O 10 ft
O 20 ft
O 40 ft
O 80 ft

Answers

Answer:

40 ft.

Step-by-step explanation:

Because James's yard is a square, we can take the square root of the area to find the side length. The square root of 100 is 10, so we know that one side of his yard will require 10 feet of fencing. Since the yard has 4 sides, we simply need to do 4 * 10 = 40 ft of fencing.

Hope this helps!

Quick answer only please

Answers

Step-by-step explanation:

The equation for circumference is

[tex]c = 2 \pi r[/tex]

Solve for circumference using the equation.

C = 2(3.14)(13)

C = 81.64 km

What type of relationship is expressed below?
f(x) = 7x +3

Answers

Answer:

Linear Function

Step-by-step explanation:

This is a linear function. A linear function is a function with the degree of 1, where the line increases continuously the whole graph. The growth of the graph is constant, making a straight line. This function is written in slope-intercept form, f(x) = mx+b. Where m is the slope and b is the y-intercept. The function will have 1 solution.

Describe how many zeros this equation will have, and where they are.
(1 Point)
f (x) = -2x2 – 5x – 2

Answers

Answer:

Let y=x

2

−5x+6, when we substitute different values of x in the equation y=x

2

−5x+6 then value of y changes accordingly.

When x=0 then

y=(0)

2

−(5×0)+6=0−0+6=6

The point is (0,6)

When x=2 then

y=(2)

2

−(5×2)+6=4−10+6=10−10=0

The point is (2,0)

When x=3 then

y=(3)

2

−(5×3)+6=9−15+6=15−15=0

The point is (3,0)

Therefore, the coordinates are (0,6), (2,0) and (3,0) and the graph of the quadratic equation y=x

2

−5x+6 is as shown above.

Hence, from above graph, we get that x=2 or x=3.

Please help

Solve the inequality.
1
x+ z
x+-3-3 or x - 3>-2
'
7.
x <
or x >[ ]
[?]

Answers

9514 1404 393

Answer:

  x ≤ -7/2 or x > 1

Step-by-step explanation:

To solve the left inequality for x, subtract 1/2 from both sides:

  x ≤ -3 -1/2

  x ≤ -7/2

__

To solve the right inequality for x, add 3 to both sides.

  x > -2 +3

  x > 1

A little Challenge.
(I made this question)
The radii of circles G and F is 1
The radii of all other circles is .5.

Answers

Step-by-step explanation:

the total area of circles =

(2 × π × 1²) + (3 × π × 0.5²)

= (2π) + ( 3× 0.25×π)

= 2π + 0.75π

= 2.75π

assume π=3.14

so, the total area =

2.75 × 3.14 = 8.635

Let's see

Area

2π(1)²+3π(0.5)²2π+0.75π2.75π8.6 units ²

Express the following as the sum of twin primes
a) 84
b)36
c)24
d)425

Answers

Answer:

answer it's c)24...

Step-by-step explanation:

i think helping you..... please tell correct or no...

Which number has a 6 that is 1/10 the value of the 6 in 6,239

Answers

Answer:

it is b

Step-by-step explanation: hope help

how to find the sum of 12 and 36 using the gcf and distributive property

Answers

I don’t really know ask Siri


At the zoo the polar bears are fed 0.1 bucket of fish a day.
The penguins are fed 0.83 that amount. How much of a
bucket are the penguins fed?

Answers

Answer:

0.083

Step-by-step explanation:

0.1 x 0.83 = 0.083

There are 0.083 bucket are the penguins fed.

What is Multiplication?

To multiply means to add a number to itself a particular number of times. Multiplication can be viewed as a process of repeated addition.

Given that;

At the zoo the polar bears are fed 0.1 bucket of fish a day.

And, The penguins are fed 0.83 that amount.

Now,

Since, At the zoo the polar bears are fed 0.1 bucket of fish a day.

And, The penguins are fed 0.83 that amount.

Hence, The bucket are the penguins fed is,

⇒ 0.83 × 0.1

⇒ 0.083

Learn more about the multiplication visit:

brainly.com/question/10873737

#SPJ2

I keep getting 30 but it’s not right. Can anyone tell me the steps?
2[10-3(4-2)]+1

Answers

Answer:

9

Step-by-step explanation:

[tex]2[10-3(4-2)]+1\\=2(10-3\times2)+1\\=2(10-6)+1\\=2\times4+1\\=9[/tex]

PLS HELP , I GOT ONLY ONE RIGHT AND THE REST ARE WRONG. I dont know what to do anymore pls help , its due todayyy plsjnn

Answers

so, you already know that angle CBD is 68 degrees, and the complementary angle to angle CBD is angle CBA. These angles together make 180 degrees because segment DBA is a straight line consisting of angles CBD and CBA. 180-68(the angle you already know) is 112 degrees for angle CBA. Then you repeat this process to find the other angles

Louis Poinsot established the patterns for the icosahedron and the dodecahedron in
1809. Besides really long words, what are they?

Answers

Answer:

Platonic solids

Step-by-step explanation:

To solve this we must be knowing each and every concept related to geometry. Therefore, icosahedron and the dodecahedron represents geometry of molecule.

What is geometry?

Molecular geometry in chemistry depicts a molecule's three-dimensional form as well as the relative location of its atomic nuclei.

Understanding a molecule's molecular geometry is critical since the spatial connection between atoms dictates its reactivity, color, bioactivity, state of matter, polarization, as well as other features. A molecule's form influences its physical and chemical properties, including its colour, sensitivity, and bioactivities. Icosahedron and the dodecahedron represents geometry of molecule.

Therefore, icosahedron and the dodecahedron represents geometry of molecule.

To learn more about geometry, here:

https://brainly.com/question/30124665

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Convert a lot size of 2/9 acre to square feet given the conversion factor: 1 acre = 43,560 ft2

Answers

Answer:

9680 ft^2

Step-by-step explanation:

1 acre = 43,560 ft^2

(2/9) acre = (2/9)*43,560 ft^2

(2/9) acre = 9680 ft^2

What is the answer to |-2|+|-3|

Answers

Answer:

5

Step-by-step explanation:

the absolute value of -2 is 2

the absolute value of -3 is 3.

Since the question is adding the absolute values, the answer is 5

A board of wood measures 58 inches thick. If you stack the boards 6212 inches high, how many boards are in the stack

Answers

Answer:

107 full and .103 of another

Step-by-step explanation:

6212/58 =

A wall is 4200 sq ft.
A gallon of paint covers 600 sq ft.
Complete the conversion factor: 1 gallon / ? sq ft

Answers

Answer:

1 gallon = 600 sq ft. So you will need 7 gallons to cover the whole wall

Step-by-step explanation:

4200 ÷ 600 = 7

Answer:

7

Step-by-step explanation:

Divide the total wall space by the amount in 1 gallon: 4200/600= 7

So you would need 7 gallons to paint the whole wall.

Is that what you were looking for?

what number divided by four equals three?

Answers

Answer:

12 divided by 4 equals 3

Step-by-step explanation:

How do you solve this: 2x+4+2=7x-6-3?

Answers

The answer you are looking for is x=3.

Solution/Explanation:

First, writing out the equation,

2x+4+2=7x-6-3.

Next, simplifying the equation just a little bit more, with the four numbers that do not include the variable "x" at all,

2x+6=7x-9.

Now, subtracting 7x from both sides of the equation,

2x+6-7x=7x-9-7x.

Regrouping the positions of the terms, using the Associative Property,

2x-7x+6=7x-7x-9.

Simplifying, and also, canceling out the 7x, since 7x-7x=0.

2x-7x+6=0-9, or 2x-7x+6=-9.

Simplifying "2x-7x," which is -5x,

-5x+6=-9.

Now, subtracting 6 from both sides,

-5x+6-6=-9-6.

Canceling out the "6," since 6-6=0,

-5x=-9-6.

Solving for "-9-6," which is "-15,"

-5x=-15.

Finally, dividing both sides by "-5,"

-5x/-5=-15/-5.

Simplifying "-5x/-5=-15/-5,"

-5x/-5=x.

And, also, -15/-5=3.

This eventually leads to x=3.

So, therefore, the final answer is x=3.

I hope that this has helped answer your question. Good day to you.

Answer:

The answer is x=3.

Step-by-step explanation:

2x+6=7x-9

-5x=-15

x=3

Consider the sequence of numbers 50,48,46,44….
(A) What are the next three numbers in this sequence?
(B) Using n to represent the position of a number in this sequence, write an expression that allows you to calculate the nth number.
(C) use your expression to find the 100th number in this sequence

Answers

Step-by-step explanation:

(A) 42,40

(B) T(n) = 50 + (n-1)(-2)

= 50+2-2n

= 52-2n

(C) T(100) = 52 - 2(100)

= 52- 200

= - 148

Write 8-10 sentences of how math was used during the pandemic


^^i didn't really understand that one and yes ill give brainliest and yes I will report your answer if you put absurd stuff

Answers

Math in many areas is used to create models, mathematical systems the describe real-world situations.

During the pandemic, a model called exponential model was used to predict the how many people will get infected given certain parameters, such as infection rate, average age of population, ...

We picked this particular model because viruses spread at an exponential rate, just like for example bacteria division would be modeled with something like [tex]2^t[/tex] where t is day number. After 1 day there are 2, after 2 days there are [tex]4, 8, 16, 32, \dots[/tex] which is known as exponential behaviour -- viruses spread that way, first person gets infected, aka patient 0, then that person likely infects others and others likely infect more people.

In particularly [tex]R_0[/tex] also known as basic reproduction number was used as a base, that is, [tex]R_0^t[/tex].

You can see if, [tex]R_0\lt 1[/tex] then we have a reciprocating behaviour, less and less infected with time passing, this is ideal and it means the pandemic is waning.

However if, like in case with current pandemic, [tex]R_0\gt 1[/tex] then the behaviour is exactly the opposite, more and more get infected with time. The current pandemic had a highest [tex]R_0[/tex] of 6.49 with a mean of 3.28 and a median of 2.76.

That means at its heighest, 1 new infected person meant potentially 6 new infected people which meant 36 because each of them would probably infect which means [tex]216,1296,7776,46656,\dots[/tex].

So the main goal is to prevent [tex]R_0[/tex] from getting larger ie. minimization, that is why vaccination, masks, good hygiene.

Of course the model is much much more complex and parameterized.

The exponential model took a lot into account and came up with various prediction graphs of for example the next week.

The graphs served to the states to decide what to do next.

So in all, everything that you are witnessing was at some point just, math.

Hope this helps :)

Answer:

it was online math cause of the pandemic

Step-by-step explanation:

what is the annual salary equivalent to a semimonthly salary of $834.08?

Answers

Answer:

$20,017.92

Step-by-step explanation:

Semimonthly means twice a month.

There are 12 months in a year.

12 x 2 = 24 (because they are payed twice a month)

24 x 834.08 = 20017.92

slove the simoltanous equation by using substitution or elimination method 5x-3y=1 3x+2y=1

Answers

By substitution method

5x - 3y =1

3x + 2y = 1

_____o____o____

[tex]5x - 3y = 1 \\ 5x = 1 + 3y \\ x = \frac{1 + 3y}{5} [/tex]

______o____o_____

[tex]3x + 2y = 1 \\ 3( \frac{1 + 3y}{5} ) + 2y = 1 \\ \frac{3 + 9y}{5} + 2y = 1 \\ \frac{3 +9y + 10y}{5} = 1 \\ \frac{3 + 19y}{5} = 1 \\ 3 + 19y = (1)(5) \\ 3 + 19y = 5 \\ 19y = 5 - 3 \\ 19y = 2 \\ y = \frac{2}{19} [/tex]

______o_____o____

[tex]x = \frac{1 + 3y}{5} = \frac{1 + 3 \frac{2}{19} }{5} \\ x = \frac{1 + \frac{6}{19} }{5} = \frac{ \frac{19 + 6}{19} }{5} = \frac{ \frac{25}{19} }{5} \\ x = \frac{25}{19} \div 5 \\ x = \frac{25}{19} \times \frac{1}{5} \\ x = \frac{5}{19} [/tex]

I hope I helped you^_^

Write a two-step equation and solve.

Four more than six times a number is 22

Five less than eleven times a number is 50

Seven less than nine times a number is -16

Answers

Step-by-step explanation:

1) let the number=x

six times a number=6x

Condition:

6x+4=22

2) eleven times a number=11x

Condition:

11x-5=50

3) nine times a number=9x

Cindition:

9x-7=-16

solve for x, need help asap!

Answers

Let's solve for x using trigonometric relation ( Cos )

we know,

[tex] \cos(30 \degree) = \dfrac{base}{hypotenuse} = \dfrac{ \sqrt{3} }{2} [/tex]

now

[tex] \dfrac{x}{8} = \dfrac{ \sqrt{3} }{2} [/tex]

[tex]x = 8 \times \dfrac{ \sqrt{3} }{2} [/tex]

[tex]x = 4 \sqrt{3} [/tex]

hence, the value of x is [tex] 4 \sqrt{3} [/tex]

simplify 81-19+218-412

Answers

Answer:

-132

Step-by-step explanation:

81+(218-19)-412

81+(199)-412

81+199-412

280-412

-132

THANK YOU

Answer:

-132

BRAINLIEST, PLEASE!

Step-by-step explanation:

Add and subtract two terms at a time until you reach the end.

Plz help me with these with steps

Answers

Answer:

10. 9/40

11. $72

Step-by-step explanation:

10.

Step 1: Have the whole cake as 1,

[tex]1-\frac{1}{8} -\frac{2}{5} -\frac{1}{4}\\= 1 -\frac{5}{40}-\frac{16}{40}-\frac{10}{40} \\= \frac{9}{40}[/tex]

11.

Step 1: Find the remaning income left

[tex]1-\frac{5}{16}-\frac{1}{4}-\frac{1}{24} -\frac{1}{48} \\= \frac{3}{8} \\[/tex]

Step 2: Calculate the weekly income

3 units = $27

1 unit = $9

Weekly income = $9 * 8 = $72

An effort of 50 N is applied to lift a load of
200 N by using a lever. If effort is displaced
through 5m to lift a load through 1m, calculate
it’s MA, VR and efficiency. Please help me

Answers

Step-by-step explanation:

hope it helps u........

Solve for y: -5(2y+3) +5=40

Answers

Answer:

Step-by-step explanation:

-5(2y + 3) +5 = 40

-10y - 15 + 5 = 40

-10y = 40 +15 - 5

-10y = 50

y =[tex]\frac{50}{-10\\}[/tex]

y = -5

The product of a rational number and an irrational number is always irrational.

A. True
B. False

Answers

A. True

The product of any rational number and any irrational number will always be an irrational number. This allows us to quickly conclude that 3π is irrational.
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