Use polar coordinates to find the limit. [if (r, θ) are polar coordinates of the point (x, y) with r ⥠0, note that r â 0+ as (x, y) â (0, 0).] (if an answer does not exist, enter dne.) lim (x, y)â(0, 0) 7eâx2 â y2 â 7 x2 + y2

Answers

Answer 1
I'll take a wild guess and suggest the limit is supposed to be

[tex]\displaystyle\lim_{(x,y)\to(0,0)}\frac{7e^{-x^2-y^2}-7}{x^2+y^2}[/tex]

Converting to polar coordinates, we take [tex]x^2+y^2=r^2[/tex] with [tex]x=r\cos t[/tex] and [tex]y=r\sin t[/tex]. This yields

[tex]\displaystyle\lim_{(r,t)\to(0,0)}\frac{7e^{-r^2}-7}{r^2}[/tex]

Most important is that the limand is independent of [tex]t[/tex]. Evaluating directly yields [tex]\dfrac00[/tex], so we apply L'Hopital's rule:

[tex]\displaystyle\lim_{r\to0}\frac{7e^{-r^2}-7}{r^2}=\lim_{r\to0}\frac{-14re^{-r^2}}{2r}=-7\lim_{r\to0}e^{-r^2}=-7[/tex]

Related Questions

What is the distance between S and T? If necessary, round to the nearest tenth.

Answers

the two triangles are similar, so the sides are proportional
36/81=48/ST
ST=108
It would be 108 km. Since PR is parallel to RT, we have to divide 81/36 to get the scale factor, which in this case would be 2.25. Then you multiply 2.25 to 48, to get 108 km.

What is the domain of the function f(x)= 1/3x+2

Answers

If it is 1/(3x+2), 3x+2≠0 =>x≠-2/3, the domain is all real number except -2/3
if it is 1/(3x)+2, 3x≠0, x≠0, the domain is all real number except 0

It is hard to tell from your equation what the demonstrator is.

The answer is the last one

x≥-6

I hope this helps, and God bless <3

Line M passes through the points (–5, 9) and (–1, 9).

Answers

Line M is a horizontal line with a slope of zero

Let me tell you why, first the y intercepts are not changing, the x intercepts are just changing which means that the line will be horizontal. You can also prove this by actually graphing the points and connecting the dots.

Two, a horizontal line always has a slope of zero, slope is rise over run, when rise = 0, no matter what the run is the slope will be zero. 
For example 0/9 = 0, 0/1 = 0. 

the sum of the measures of the three of a angles of triangle is 180. In a triangle, the measures of three angles are x,x-5 and x+23. What is the measure of each angle

Answers

x + x-5 + x +23 = 180

 combine like terms:

3x +18 = 180

 subtract 18 from each side:

3x = 162

divide both sides by 3

x = 162 / 3 = 54

Angle x = 54 degrees

 Angle x-5 = 54-5 = 49 degrees

Angle x +23 = 54 +23 = 77 degrees

Which graph represents the function y=2/3x-2

Answers

We can graph y = 2x/3 - 2 to find the line.

We know one point, which is the y-intercept. The y-intercept is (0,-2) so that is our first point. Plot that point on the chart. Now to find another point, we can just insert a number for x and solve for y. I am going to use the number 3.

 y = 2x/3 - 2 
 y = 2(3)/3 - 2 
 y = 6/3 - 2 
 y = 2 - 2 
 y = 0
So when x = 3 y = 0. We have another point,which is (3,0) Plot the points (0, -2) (3, 0) and draw a line between the points and that is your graph. It will look the image I attached.



Answer:

Here you go! used a graphing calculator for accuracy.

Step-by-step explanation:

there are seven days how many days are there in 16 weeks

Answers

There are 112 days in 16 weeks because all you have too do is take 16 and multiply it by 7 which gets you 112. Hope this helped.
it would be 112 days :-)
16 x 7 = 112 

Prove that if b is a square matrix then b+b^t is symmetric

Answers

A matrix [tex]\mathbf X[/tex] is symmetric if [tex]\mathbf X=\mathbf X^\top[/tex]. We have

[tex](\mathbf B+\mathbf B^\top)^\top=\mathbf B^\top+(\mathbf B^\top)^\top=\mathbf B^\top+\mathbf B=\mathbf B+\mathbf B^\top[/tex]

and so [tex]\mathbf B+\mathbf B^\top[/tex] is indeed symmetric.

An animal park has 120 gazelles. If the population increase 5% in on year, how many gazelles will the park have next year?

Answers

five percent of 120 is 6 because 120*0.05=6. add 6 to 120 and we have the answer 126 gazells next year

The number of gazelles will the park have next year will be 126 if An animal park has 120 gazelles. If the population increase 5% in on year.

What is percentage?

It's the ratio of two integers stated as a fraction of a hundred parts. It is a metric for comparing two sets of data, and it is expressed as a percentage using the percent symbol.

It is given that:

An animal park has 120 gazelles. If the population increase 5% in on year,

= 5% of 120

= 6

= 6 + 120

= 126

Thus, the number of gazelles will the park have next year will be 126 if An animal park has 120 gazelles. If the population increase 5% in on year.

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Find 14/15−1/3 . Write your answer as a fraction in simplest form.

Answers

The answer is 3/5. Hope this helps! :D

~PutarPotato

Which product represents the fraction of the circle that is shaded?

A. 3/4 x 1/2
B. 2/3 x 3/4
C. 1/4 x 3/4
D 3/4 x 3/4

Answers

Answer:

D 3/4 × 3/4

Step-by-step explanation:

The part of the circle that is black is 1/4 of the circle. The remaining 3/4 is divided by the dashed lines into 4 equal parts, so each of those parts is 1/4 of 3/4 of the circle. 3 of the parts are shaded blue, so those represent ...

... 3/4 × 3/4 . . . of the circle

Final answer:

The correct product that represents the fraction of the shaded circle is D. 3/4 x 3/4.

Explanation:

The correct answer is D. 3/4 x 3/4.

The fraction represents the shaded part of the circle. We can determine the shaded area of the circle by multiplying the fraction of the radius by the fraction of the circumference that is shaded. In this case, 3/4 x 3/4 would yield a product that represents the fraction of the circle that is shaded.

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what is the value of this expression when x = -1 and y = 2?

4x³y²

Answers

Substituting in you get 4(-1)^3 * (2)^2. -1 cubed is -1 and 2 squared is 4. So you get -4*4 = -16 as your answer.

after taking 1/4 pound of flour from a canister to make muffins, maria has 7/8 of the flour left. If each batch of muffins requires 2/5 pound of flour, find the greatest number of batches of muffins that Maria can make using the remaining flour/

Answers

You need a common denominator to calculate the amount of flour left, the easiest is 40 since 5*8 is 40 and 8*5 is 40. So you multiply the fractions to make them common by 40, you have 35/40 flour left and need 16/40 per batch. 16 goes into 35 2 times and you would have 3/40 of flour left.

what is a decimal number which never ends, but whose digits after the decimal point come in a predictable pattern called? it starts with the letters re.

Answers

repeating decimals.....I think that is what you mean
Repeating decimal which never ends, but whose digits after the decimal point come in a predictable pattern.

Barbara D’Angelo’s bank granted her a single-payment loan of $1,000 for 100 days at 12% ordinary interest. What is the amount of ordinary interest owed?

Answers

The formula is
I=prt
I interest owed?
P principle 1000
R interest rate 0.12
T time 100days/360days
360 days in a year which ordinary interest means
I=1,000×0.12×(100÷360)
I=33.33. ..Answer

Hope it helps!

A rectangular room is 22 meters longer than it is wide, and its perimeter is 1616 meters. find the dimension of the room.

Answers

w= width; L= length =w+22m; p= perimeter= 2(L+w)
1616 meters= 2 (L+w) substitute for L
1616m+ 2(w+22m+w) divide each side by 2

808m= 2w+22m subtract 22m from each side
786m=2w divide each side by 2
393m=w Anwer: The width is 393 meters
L=w+22m=393m+22m=415m Answer: The length is 415 meters

A six-sided rectangular box is to hold 1/2 cubic meter; what shape should the box be to minimize surface area?

Answers

A circle is an object which has the lowest surface area to volume ratio. So in this case, the shape should be like that of a circle but we cannot have a circle here because we want to form a 6 sided box. So the next thing closer to circle is a square. Hence the shape should be a square:

 

Answer:

square

Final answer:

To minimize surface area for a given volume of 1/2 cubic meter, the box should be shaped as a cube with each side measuring approximately 0.7937 meters. This cube shape offers the smallest surface area for the given volume.

Explanation:

To minimize the surface area of a six-sided rectangular box with a volume of 1/2 cubic meter, it is best to make the box in the shape of a cube. This shape has the smallest surface area for a given volume. To find the dimensions of the box, let's denote the side of the cube as 's'. We know that volume V of a cube is given by V = s³. So, if the volume is 1/2 cubic meter, we have:

s³ = 1/2

s = ∛(1/2) ≈ 0.7937 meters

Each side of the cube should be approximately 0.7937 meters to achieve the minimal surface area. The surface area SA of the cube can be calculated as:

SA = 6s²

SA = 6 × (0.7937)² ≈ 3.770 meters²

Thus, a cube with sides of about 0.7937 meters will have the minimal surface area for a volume of 1/2 cubic meter.

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Last year Mr. Henderson paid a total of $98.40 for phone service and $79.20 for garbage pick up what was his average cost per month for phone service and garbage pick up?

Answers

To calculate the values do x / 12

So 98.4 / 12 = 8.2 and next part 79.2 / 12 = 6.6

Mr. Henderson spent $8.2 a month for phone service and $6.6 for garbage pick up.
Let A = average for both

A = (97.40 + 79.20)/2

You finish.

A cube has a volume of 512 mm^3. If all sides of the cube are divided by 4, what will the resulting volume be?

A) 8 mm^3
B) 27 mm^3
C) 7.2 mm^3
D) 12 mm^3

Answers

[tex]\bf \textit{volume of a cube}\\\\ V=s^3\qquad \boxed{s=\frac{s}{4}}\implies V=\left( \cfrac{s}{4} \right)^3\implies V=\cfrac{s^3}{4^3}\implies V=s^3\cdot \cfrac{1}{4^3} \\\\\\ V=s^3\cdot \cfrac{1}{64}\impliedby \frac{1}{64}\textit{ of the original volume, if the original was 512} \\\\\\ 512\cdot \cfrac{1}{64}\implies \cfrac{512}{64}[/tex]

Officer Brimberry wrote 8 tickets for traffic violations last week, but only 5 tickets this week. What is the percent decrease? Give your answer to the nearest tenth of a percent.

Answers

(Last weeks value-this weeks value)/(Last weeks value)
(8-5)/(8)
3/8=0.375
*100 to get percentage
0.375*100=37.5% decrease

Answer:

The percent decrease is [tex]37.5\%[/tex]

Step-by-step explanation:

we know that

[tex]8\ tickets[/tex] ------> represent the [tex]100\%[/tex]

so

by proportion

Find the percent decrease

[tex]\frac{100}{8}\frac{\%}{tickets} =\frac{x}{(8-5)}\frac{\%}{tickets} \\ \\x=100*(8-5)/8\\ \\x=100*3/8\\ \\x=37.5\%[/tex]

6.14 x 10 to the power of negative 9 in standard form

Answers

6.14 x 10^-9 = 0.00000000614
0.00000000614 is the standard form

Which statement proves that PQRS is a parallelogram? The slopes of SP and RQ are both –2 and SP = RQ = . The slopes of RS and QP are both 3 and SP = RQ = . The midpoint of RP is and the slope of RP is . The midpoint of SQ is and SQ = 5

Answers

Answer:

The correct option is 1. The figure PQRS is a parallelogram, if slope of SP and RQ are both –2 and SP = RQ.

Step-by-step explanation:

The opposite sides of a parallelogram are parallel are equal.

In the quadrilateral PQRS,

PQ and RS are opposite sides.

SP and RQ are opposite sides.

The slope of two parallel lines are same.

If the slopes of SP and RQ are both –2. It means SP and RQ are parallel. It is also given that

SP = RQ

Since one pair of opposite sides are equal and parallel, therefore the another set of opposite sides is also parallel and equal.

The opposite sides are prallel and equation, so the quadrilateral PQRS is a parallelogram.

Thus correct option is 1.

The statement that proves that quadrilateral PQRS is a parallelogram is: A. The slopes of SP and RQ are both –2 and SP║RQ.

Properties of the Sides of a Parallelogram

A parallelogram is a quadrilateral having two pairs of opposite sides that are equal and parallel to each other, and also, the slopes of opposite sides of a parallelogram are the same.

Therefore, the statement that proves that quadrilateral PQRS is a parallelogram is: A. The slopes of SP and RQ are both –2 and SP║RQ.

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after 9 months, the simple interest earned on an investment of $1200 is $72. find the interest rate.

Answers

Use the formula i=prt, where i is the interest earned, p is the principal, r is the rate (as a decimal fraction) and t is the elapsed time, in years.

Here i = $72 = $1200 r (9/12)                    (9 months is 9/12, or 3/4, of 1 year)
Reducing, 
              $72 = $900r
                                          Solving for r, r=0.08, or 8 percent per year.

The length of a rectangle is given by 5t+4sqrt(t), and its height is sqrt(t), where t is time in seconds and the dimensions are in centimeters. Fine the rate of change of the area of the rectangle with respect to time when the length of the rectangle is 9 centimeters.

Answers

Answer:

11.5 cm²/s

Step-by-step explanation:

We must solve two problems to answer this question:

find the time at which the length is 9 cmfind the rate of change of area with respect to time (at that time)

For the first problem, we have ...

... 9 = 5t +4√t

... 9 -5t = 4√t . . . . . subtract 5t

... 81 -90t +25t² = 16t . . . . square both sides

... 25t² -106t +81 = 0 . . . subtract 16t

... (t -1)(25t -81) = 0 . . . . factor

... t = 1 or 3.24 . . . . . . t=3.24 is an extraneous solution

_____

For the second problem, we have area (a(t)) is ...

... a(t) = length×height = (5t +4√t)(√t) = 5t^(3/2) +4t

Then the derivative is ...

... a'(t) = (3/2)(5√t) +4

and

... a'(1) = (3/2)(5√1) +4 = 11.5 . . . . . cm²/s

_____

Comment on the attachment

A graphing calculator can help solve both problems. It can help find the time at which length is 9 cm by solving ... length-9 = 0. (The nice thing here is that there is no extraneous solution.) It can compute the derivative of a function, too.

if it takes Joan one and a half hours to watch a movie, how many films can he watch in ten and a half hours

Answers

7 hours 
steps: 

10 1/2 divided by 1 1/2

Marika Perez’s gross biweekly pay is $2,768. Her earnings to date for the year total $80,272. What amount is deducted from her pay for Social Security taxes if the rate is 6.2%? What amount is deducted for Medicare, which is taxed at 1.45%?

Answers

Answer:

The deduction for social Security tax is $4976.86 and the deduction for Medicare tax is $1163.94 .

Step-by-step explanation:

Marika Perez’s gross biweekly pay is $2,768. Her earnings to date for the year total $80,272.

What amount is deducted from her pay for Social Security taxes if the rate is 6.2%?

[tex]0.062\times80272=4976.86[/tex] dollars

What amount is deducted for Medicare, which is taxed at 1.45%?

[tex]0.0145\times80272=1163.94[/tex] dollars

if 2 out of every 20 ducks were banded, What percent were not​ banded?

Answers

90% are not banded ducks

if 2 were banded that means 18 out of 20 were not banded

 18 divided by 20 = 0.9

 so 90% were not banded

Tina has put 15 of her old CDs in a storage crate. How many more CDs can she store in the crate if it can hold no more than 23 CDs

Answers

23-15=8 I think the answer is 8


Since she can only have 23 in the crate, and she already has 15, you subtract 15 from 23.

23 - 15 = 8

She can only fit 8 more CDs.

Hope this helps!


Jack is mowing a lawn that has a shed. Jack wants to know the area of the lawn he has to mow. here are the dimensions of the yard and the shed. 13x-4 length 5x withd shed is 2x+4length withd is 2x
find a polynomial that describes the area of the lawn he has to mow. i.e. find the area of the area of the shed.

Answers

We know that the formula for area is simply:

area = l w

where l is length and w is width

 

yard dimensions: l = 13x – 4, w = 5x

Ayard = (13x – 4) 5x = 65x^2 – 20x

 

shed dimensions: l = 2x + 4, w = 2x

Ashed = (2x + 4) 2x = 4x^2 + 8x

 

Therefore the area to mow is:

Amow = Ayard – Ashed

Amow = 65x^2 – 20x – (4x^2 + 8x)

Amow = 65x^2 – 20x – 4x^2 – 8x

Amow = 61x^2 – 28x

What is another way to write 46

Answers

Final answer:

The number 46 can be written as 'forty-six', 'XLVI' in Roman numerals, '101110' in binary, '56' in octal, '2E' in hexadecimal, a sum or product of other numbers, or in scientific notation as 4.6 x 10ⁱ.

Explanation:

There are several ways to write the number 46 in mathematics. One alternative way to express the number is by using words, such as 'forty-six'. Another method is to use Roman numerals, which would be 'XLVI'. Additionally, 46 can be represented in other numerical bases; for example, in binary, it is '101110', in octal, it is '56', and in hexadecimal, it is '2E'. If we dive into mathematics, 46 can also be written as a sum of other numbers, such as 23 + 23, or a product of primes, which for 46 is 2 x 23. Lastly, 46 can be expressed in scientific notation as 4.6 x 10±, though this form is more commonly used for very large or very small numbers.

Every 3 days Marco fills up his car with gas. Every 8 days he washes his car. On what day will Marco fill his car with gas and wash it?

Answers

I the week starts on Monday he will fill Monday and Saturday and on each Monday he will wash his car
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With half the dogs stillover their traces, he cried Mush on! and leaped upon the sled just as the pursuers dashedabreast of him.The Irishman was preparing to spring for himthey were so sure they had him that they didnot shootwhen Walt turned fiercely upon them with his whip. He struck at their faces, andmen must save their faces with their hands. So there was no shooting just then. Before theycould recover from the hot rain of blows, Walt reached out from his sled, catching theirwheel dog by the forelegs in midspring, and throwing him heavily. This snarled the team,capsizing the sled and tangling his enemies up beautifully.Away Walt flew, the runners of his sled fairly screaming as they bounded over the frozensurface. And what had seemed an accident proved to be a blessing in disguise. The properlead dog was now to the fore, and he stretched low and whined with joy as he comrades along.By the time he reached Ainslies Creek, seventeen miles from Dawson, Walt had left hispursuers, a tiny speck, far behind. At Monte Cristo Island he could no longer see them. Andat Swede Creek, just as daylight was silvering the pines, he ran plump into the camp of oldLoren Hall.Almost as quick as it takes to tell it, Loren had his sleeping furs rolled up, and had joined Walt on the sled. They permitted the dogs to travel more slowly, as there was no sign of thechase in the rear, and just as they pulled up at the gold commissioners office in Dawson,Walt, who had kept his eyes open to the last, fell asleep.And because of what Walt Masters did on this night, the men of the Yukon have becomeproud of him, and speak of him now as the King of Mazy May.6. 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