You can check that both series converge for all real x (say, using the ratio test).
Now,
[tex]\displaystyle e^x = \sum_{n=0}^\infty \frac{x^n}{n!} \implies x e^{-x^2/2} = \sum_{n=0}^\infty \frac{(-1)^n x^{2n+1}}{2^n n!}[/tex]
and if you have some familiarity with differential equations, you might recognize that the second series represents a Bessel function, namely
[tex]\displaystyle I_0(x) = \sum_{n=0}^\infty \frac{x^{2n}}{2^{2n} (n!)^2}[/tex]
but we won't bother making use of this.
In the integral, we interchange the integral with the sum
[tex]\displaystyle \int_0^\infty x e^{-x^2/2} \sum_{n=0}^\infty \frac{x^{2n}}{2^{2n} (n!)^2} \, dx = \sum_{n=0}^\infty \frac1{2^{2n} (n!)^2} \int_0^\infty x^{2n+1} e^{-x^2/2} \, dx[/tex]
and consider the sequence of integrals,
[tex]J_n = \displaystyle \int_0^\infty x^{2n} x e^{-x^2/2} \, dx[/tex]
Integrating by parts with
[tex]u = x^{2n} \implies du = 2n x^{2n-1} \, dx[/tex]
[tex]dv = x e^{-x^2/2} \, dx \implies v = -e^{-x^2/2}[/tex]
Then the contribution of uv is 0, so
[tex]J_n = \displaystyle 2n \int_0^\infty x^{2(n-1)} x e^{-x^2/2} \, dx = 2n J_{n-1}[/tex]
We have
[tex]J_0 = \displaystyle \int_0^\infty x e^{-x^2/2} \, dx = 1[/tex]
so that
[tex]J_n = 2n J_{n-1} = 2n (2(n-1)) J_{n-2} = 2n (2(n-1)) (2(n-2)) J_{n-3}[/tex]
and so on; after k steps,
[tex]J_n = 2n (2(n-1)) (2(n-2)) \cdots (2(n-(k-1))) J_{n-k}[/tex]
so that when n = k,
[tex]J_n = 2n (2(n-1)) (2(n-2)) \cdots 2 J_0 = 2^n n![/tex]
Then the integral we want is
[tex]\displaystyle \int_0^\infty x e^{-x^2/2} \sum_{n=0}^\infty \frac{x^{2n}}{2^{2n} (n!)^2} \, dx = \sum_{n=0}^\infty \frac{2^n n!}{2^{2n} (n!)^2} = \sum_{n=0}^\infty \frac1{2^n n!}[/tex]
and knowing the series expansion for [tex]e^x[/tex], it follows that the integral has a value of [tex]e^{1/2} = \boxed{\sqrt{e}}[/tex]
Emma's family traveled 5/8 of the distance to her aunt’s house on Saturday. They traveled 1/3 of the remaining distance on Sunday. What fraction of the total distance to her aunt’s house was traveled on Sunday?
Answer:
23/24
Step-by-step explanation:
To find the total distance of Sunday and Saturday we add 5/8 + 1/3
= 5/8 + 1/3
= 5 × 3/8 × 3 + 1 × 8/3 × 8
= 15/24 + 8/24
= 15 + 8/ 24
= 23/24
How do I get the y-coordinates?
Answer:
Plug the x values into the equation and the answers are the y values
Researchers from the Educational Testing Service (ETS) found that providing immediate feedback to students answering openended questions can dramatically improve students’ future performance on exams ( Educational and Psychological Measurement, Feb. 2010). The ETS researchers used questions from the Graduate Record Examination (GRE) in the experiment. After obtaining feedback, students could revise their answers. Consider one of these questions. Initially, 50% of the students answered the question correctly. After providing immediate feedback to students who answered incorrectly, 70% answered correctly. Consider a bank of 100 open-ended questions similar to those on the GRE. (b) After providing immediate feedback, what is the probability that more than 10 of the students answer the question correctly? Group of answer choices 58.8% 41.2% 95.2% 4.8%
Complete question is;
Researchers from the Educational Testing Service (ETS) found that providing immediate feedback to students answering openended questions can dramatically improve students’ future performance on exams (Educational and Psychological Measurement, Feb. 2010). The ETS researchers used questions from the Graduate Record Examination (GRE) in the experiment. After obtaining feedback, students could revise their answers. Consider one of these questions. Initially, 50% of the students answered the question correctly. After providing immediate feedback to students who answered incorrectly, 70% answered correctly. Consider a bank of 100 open-ended questions similar to those on the GRE. a. In a random sample of 20 students, what is the probability that more than half initially answer the question correctly? b. Refer to part a . After providing immediate feedback, what is the probability that more than half of the students answer the question correctly?
Answer:
A) 41.2%
B) 95.2%
Step-by-step explanation:
This is a binomial probability distribution problem, so we will use the formula;
P(k) = (n!/(k!(n - k)!) × p^(k) × (1 - p)^(n-k)
A) Initially, 50% of the students answered the question correctly.
Thus, p = 0.5
Also,n = 20
Now, the probability that more than half initially answer the question correctly would be:
P(k > 10)
This can be expressed as;
P(k > 10) = P(11) + P(12) + P(13) + P(14) + P(15) + P(16) + P(17) + P(18) + P(19) + P(20)
P(11) = (20!/(11!(20 - 11)!) × 0.5^(11) × (1 - 0.5)^(20-11) = 0.1602
Similarly,
P(12) = (20!/(12!(20 - 12)!) × 0.5^(12) × (1 - 0.5)^(20-12) = 0.1201
P(13) = (20!/(13!(20 - 13)!) × 0.5^(13) × (1 - 0.5)^(20-13) = 0.0739
Using online binomial probability calculator we can get the remaining values which are;
P(14) = 0.037
P(15) = 0.0148
P(16) = 0.0046
P(17) = 0.0011
P(18) = 0.0002
P(19) = 0.00002
P(20) = 0
Thus;
P(k > 10) = 0.1602 + 0.1201 + 0.0739 + 0.037 + 0.0148 + 0.0046 + 0.0011 + 0.0002 + 0.00002 + 0 ≈ 0.41192 = 41.2%
B) After providing immediate feedback, we are told that 70% answered correctly.
Thus; p = 70% = 0.7
Similar to A above and using online binomial probability calculator, we have;
P(11) = 0.0654
P(12) = 0.1144
P(13) = 0.1643
P(14) = 0.1916
P(15) = 0.1789
P(16) = 0.1304
P(17) = 0.0716
P(18) = 0.0278
P(19) = 0.0068
P(20) = 0.0008
Thus;
P(k > 10) = 0.0654 + 0.1144 + 0.1643 + 0.1916 + 0.1789 + 0.1304 + 0.0716 + 0.0278 + 0.0068 + 0.0008 = 0.952 = 95.2%
John has 12 pounds of dog food and is going to separate it into 3/4 pound portions. How many portions of dog food will he have?
HELP!
16 portions
explanation:
12 / 3/4
= 12 * 4/3
= 4*4 = 16
root of 6x^2 -8 = -8x
Answer:
If your question is set up like this [tex]\sqrt{6x^2-8}=-8x[/tex] then your answer is No solution.
If your question is set up like this[tex]\sqrt{6x^2}-8=-8x[/tex] then your answer is [tex]x=\frac{4(8-\sqrt{6}) }{29}[/tex] or x = 0.765
Hope this helps!
can someone answer real quick
Answer:− -19s
Step-by-step explanation:
Move
Joyce paid $143.00 for an item at the store that was 35 percent off the original price. What was the original price?
Answer:
220
Step-by-step explanation:
GIven:
Joyce paid $143.00 for an item at the store that was 35 percent off the original price.
To Find:
What was the original price?
Solution:
Since that was 35 percent off the original price
Thus, 100 - 35 = 65
Equation:
143 = 0.65x
DIvide both sides by 0.65
143/0.65 = 0.65x/0.65
x = 220
Check Answer:
220 x 65% = 143
~Lenvy~
i’ll mark brainlest to whoever answers this question first! :)
Where is my buddy? Helllo buddy nice to see you
Answer:
[tex]\sf\fbox\red{Answer:-}[/tex]
gud noon!
dopamine is responsible for how we feel pleasure
[tex]\small\fbox{\blue{\underline{mαrk \; mє \; вrαínlíєѕt \; plєαѕє ♥}}}[/tex]
Determine whether each of the following statements is true or false. a. The least-squares regression line is the line that makes the square of the correlation in the data as large as possible. False b. The least-squares regression line is the line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible True c. The least-squares regression line is the line that best splits the data in half, with half of the points above the line and half below the line. False d. The least-squares regression line always passes through the point (x-bar,y-bar ), the means of the explanatory and response variables, respectively. True
Answer:
Options A & C are False while Options B & D are true.
Step-by-step explanation:
The definition of least squares regression line is given as;
The Least Squares Regression Line is a line that normally causes the vertical distance from the data points to the regression line to be as small as possible.
The term “least squares” is derived from the fact that the best line of fit is one that minimizes the the sum of squares of the errors which is also called the variance.
From this definition above, we can see that options A and C are false while option B is the perfect definition for the least line of squares.
Now, the point (x-bar,y-bar ) is known as the mean.
However, every least squares must pass through the middle point of the given data. The mean is the middle point of data in regression analysis. Thus, we can infer that the least-squares regression line always passes through the mean which is point (x-bar,y-bar ). Thus, option D is true.
The back of Alisha's property is a creek. Alisha would like to enclose a rectangular area, using the creek as one side and fencing for the other three sides, to create a pasture. If there is 380 feet of fencing available, what is the maximum possible area of the pasture?
9514 1404 393
Answer:
18050 square feet
Step-by-step explanation:
Let x represent the length of fence parallel to the creek. Then the remaining 380-x feet of fence is divided between the two ends of the pasture. The area will be the product ...
A = (x)(1/2)(380 -x)
The graph of this is a parabola that opens downward. It has x-intercepts at x=0 and x=380. The vertex (maximum) will be on the line of symmetry, halfway between these zeros, at x = (0 +380)/2 = 190.
Then the area is ...
A = (190 ft)(1/2)(380 -190 ft) = (190 ft²)/2 = 18,050 ft²
The maximum possible area of the pasture is 18,050 square feet.
HELP PLEASE!!!!!! + 100 POINTS
Solution:
Given:
x = 10Substitute the value of x into the expression.
[tex]5\sqrt{x - 1} + 9[/tex]
[tex]\rightarrow 5\sqrt{10 - 1} + 9[/tex]
Simplify the root:
[tex]\rightarrow5\sqrt{9} + 9[/tex]
[tex]\rightarrow(5 \times \sqrt{9}) + 9[/tex]
[tex]\rightarrow(5 \times 3) + 9[/tex]
Multiply 5 and 3:
[tex]\rightarrow15 + 9[/tex]
Add 15 and 9:
[tex]\rightarrow24[/tex]
helppppppppppppppppp
Answer:
31-32
Hyposis: SHe is the mother.
Conclusion: She's not.
Step-by-step explanation:
The verbal expression “the difference between
three times a number x and 12, increased by the quotient of 5 and the number x" is equivalent to which algebraic expression?
A. 3(x-1)+x/5
B. (3x-12)+5/x
C. 3(x-12)+5+x
D. (3x-12)+5x+x
Answer:
B. (3x-12)+5/x
Step-by-step explanation:
Difference means - or minus
Three times a number x and 12= 3x-12
Increased= + or plus
quotient= / or divide
5 and the number x= 5/x
So the answer is,
(3x-12)+5/x
I hope you understand.
Pete can do a job in 50 minutes while his brother Jim can do it in 1/2 the time. How long will it take them to do the job working together? (50/3 min)
It will take them 20 minutes to do the job working together.
Working time calculationGiven that Pete can do a job in 50 minutes while his brother Jim can do it in 1/2 the time, to determine how long it will take them to do the job working together, the following calculation must be performed:
1/1 + 2/1 = 3/11 / (3/1) = 1/360 min / 3 = 20 minTherefore, it will take them 20 minutes to do the job working together.
Learn more about working time calculation in https://brainly.com/question/536439
Rational function
g(x) = 1 / (x-3) +2
Find x and y intercepts
Graph
Answer:
[tex]x \: intercept = ( \frac{5}{2} ,0) \\ y \: intercept = (0, \frac{5}{3} )[/tex]
Step-by-step explanation:
STEP 1: Define x and y intercepts
The x-intercept is where a line crosses the x-axis, and the y-intercept is the point where the line crosses the y-axis.
Step 2: We plot the graph of the given function
The graph can be seen in the graph image I sent. The x and y intercepts are also identified.
what unit of measurement would you use to weigh a elephant Oz * mm lb
Answer:
You would use lbs.
Step-by-step explanation:
mm is a unit of distance.
Oz is too small of a unit for weight.
lbs are just right!
The price of a cd was decreased by 2% to £14. What was the price before the decrease?
Give your answer to the nearest penny.
Answer:
14.28
Step-by-step explanation:
2% of 14 is .28
.28 + 14 = 14.28
Hi!
Since the price was decreased by 2%, that means that 14 is 98% (100% - 2%) of the original price. So, we just have to figure out 98% of what number is 14.
98% can be written in decimal form as 0.98.
We can set up the following equation:
14 = 0.98x
Now, divide both sides by 0.98:
14/0.98 = 14.2857143
The question says to round to the nearest penny, so your answer is
14.29Net A has 3 rectangles with 2 triangles on the side. Net B has 3 rectangles with 2 triangles on the sides.
Students in Mrs. Garcia’s class were practicing drawing nets. She gave them the three-dimensional figure shown. Alina drew the net labeled A and Benjamin drew the net labeled B. What statement about the students’ nets is true?
Alina drew the only correct net.
Benjamin drew the only correct net.
Both nets are correct.
Neither student’s net is correct.
Answer:
c
Step-by-step explanation:
Answer:
~c~
Step-by-step explanation:
Exercises
1.
Create a real-world situation that relates to the points shown in the number line model. Be sure to describe the
relationship between the values of the two points and how it relates to their order on the number line.
0
A real-world situation to model the number line is: It was colder on Friday night than Saturday morning because 0 is greater than -1
How to interpret the number line?See attachment for the number line
From the figure, we have the following points
0 and -1
The number line can be modelled by temperature where a colder temperature is represented by 0, while the other temperature is -1 degrees Celsius
Hence, a complete scenario is:
On a Friday night, the measure of the temperature is 0 degrees Celsius. On Saturday morning, the temperature is -1 degree Celsius. It was colder on Friday night than Saturday morning because 0 is greater than -1
Read more about number lines at:
https://brainly.com/question/10851163
PLEASE SOLVE IT
DONT STEAL POINYS!!
Answer:
A) 3
Step-by-step explanation:
Method 1)Ques: 30/(4√3 + 3√2) = 4√3 - a√2
Rationalise the denominator.
→ 30/(4√3 + 3√2) × (4√3 - 3√2)/(4√3 - 3√2) = 4√3 - a√2
→ (120√3 - 90√2)/(48 - 18) = 4√3 - a√2
→ (120√3 - 90√2)/30 = 4√3 - a√2
→ 120√3 - 90√2 = 120√3 - 30a√2
→ 90√2 = 30a√2
On solving we get,
→ a = 3
Method 2)Ques: 30/(4√3 + 3√2) = 4√3 - a√2
→ 30 = 4√3(4√3) + 4√3(-a√2) + 3√2(4√3) + 3√2(-a√2)
Solve the brackets,
→ 30 = 48 - 4a√6 + 12√6 - 6a
→ - 18 = - 4a√6 - 12√6 - 6a
Put like terms on one side,
→ - 18 + 6a = - 4√6 (a + 3)
Take the common,
→ 3(a - 3) = - 2√6 (a + 3)
→ 3 (a - 3) = 2√6 (-a - 3)
→ [3(a - 3)]/2√6 = - a - 3
Rationalise the denominator,
→ 2√6(3a - 9)/24 = - a - 3
→ (3a√6 - 9√6)/12 = - a - 3
→ √6(a - 3) = - 4a - 12
Do squaring on both sides,
→ [√6(a - 3)]² = - (4a + 12)²
→ 6(a² + 9 - 6a) = - (16a² + 144 + 96a)
Solve the brackets,
→ 6a² + 54 - 36a = - 16a² - 144 - 96a
→ 22a² - 132a + 198 = 0
→ 11a² - 66a + 99 = 0
→ a² - 6a + 9 = 0
Split the middle term,
→ a² - 3a - 3a + 9 = 0
→ a(a - 3) -3(a - 3) = 0
→ (a - 3)(a - 3) = 0
On comparing we get,
→ a = 3 (key to solve this and similar questions is rationalisation of the denominator)
Hence, the correct option is option A) 3.
A line is drawn parallel to y = x. It has the same slope, so it’s equation has the form y = x + b. The new line passed through the point (2, 5). What is its y- intercept (b)?
Answer:
b = 3
Step-by-step explanation:
(2,5) is information! x = 2 and y = 5.
Use these values in the equation:
y = x + b
5 = 2 + b
Subtract 2.
3 = b
The equation of the line is y = x + 3.
Will Mark Brainliest!!!
A diver is standing on a platform 24 ft above a pool. He jumps from the platform with an initial
upward velocity of 8 ft/s. Using the formula, h(t) = -16t2 + vt + s, where h is his height
above the water, t is the time, v is his starting upward velocity, and s is his starting height.
A) After how long will the diver reach its maximum height?
B) What is the maximum height the diver will reach?
Answer:
he Formula h = -16t^2 + vt + s; where
h = height after t seconds
t = time in seconds
v = upward velocity
s = initial height (t=0)
also note that
-16t^2 represents the downward force of gravity for t seconds
+vt = the upward force for t seconds
:
the height when he hits the water = 0 therefore:
0 = -16t^2 + 8t + 24
usually written
-16t^2 + 8t + 24 = 0
we can simplify this, divide by -8, then we have
2t^2 - t - 3 = 0
this will factor to
(2t - 3)(t + 1) = 0
the positive solution
2t = 3
t = 3/2
t = 1.5 seconds to hit the water
-
Form the actual equation
y=-16t²+vt+sy=-16t²+8t+24Find vertex as vertex is maximum
x coordinate
-b/2a-8/2(-16)8/321/4s0.25sy coordinate
h(0.25)-16(0.25)²+8(0.25)+2425mMax height is 25m
Time to reach is 0.25s
How did I get this wrong????
Answer:
18.98°
Step-by-step explanation:
1) p=arcsin(13/40);
2) p=arcsin0.325≈18.98°.
Long Division: (3x^4-8x^3-x^2+9x+5) / (x-2) pleaseee answer this
3x⁴ = 3x³ • x, and
3x³ (x - 2) = 3x⁴ - 6x³
Subtract this from the numerator to get a remainder of
(3x⁴ - 8x³ - x² + 9x + 5) - (3x⁴ - 6x³) = -2x³ - x² + 9x + 5
-2x³ = -2x² • x, and
-2x² (x - 2) = -2x³ + 4x²
Subtract this from the previous remainder to get a new remainder of
(-2x³ - x² + 9x + 5) - (-2x³ + 4x²) = -5x² + 9x + 5
-5x² = -5x • x, and
-5x (x - 2) = -5x² + 10x
Subtract this from the last remainder to get a new one of
(-5x² + 9x + 5) - (-5x² + 10x) = -x + 5
-x = -1 • x, and
-1 (x - 2) = -x + 2
This gives a new remainder of
(-x + 5) - (-x + 2) = 3
3 does not divide x, so we're done.
So, we have
(3x⁴ - 8x³ - x² + 9x + 5) / (x - 2) = 3x³ - 2x² - 5x - 1 + 3/(x - 2)
An iPad is marked down from $700 to $575. What is the percent markdown of the iPad?
Solution:
the percent markdown of the iPad is 17.86%
Given:
Original Price = $700
Final price = $575
The markdown is gotten by;
[tex]Markdown=original~price-final~price[/tex]
[tex]Markdown=700-575[/tex]
Markdown = $125
Thus, the percent markdown is gotten by;
[tex]percent~markdown=\frac{markdown}{original~price}~x~ 100[/tex]
percent markdown = [tex]\frac{125}{700}[/tex] × 100%
percent markdown =[tex]\frac{12500}{700}[/tex]
percent markdown = 17.857 %
percent markdown ≈ 17.86%
Therefore, the percent markdown of the iPad is 17.86%
Hope this helps!!
If you have any questions please ask.
I need to know this hard wuestion!
The value '0' is between the points above sea level and points below sea level. '0' being neither negative nor positive means it cannot be below or above sea level, rather '0' meters represents sea level.
Hope that helps!
Which is a parallelogram? For points A B C D
Explanation:
Any parallelogram has two pairs of opposite sides that are parallel.
A rectangle is a parallelogram, but not the other way around.
Choices A and B are trapezoids with exactly one pair of parallel sides.
What is the prime factorization of 32?
OA) 232
OB) 23
OD) 28
I
Answer:
2 × 2 x 2 x 2 x 2 or 25
Answer:
2*2*2*2*2, which can be also written as [tex]2^5[/tex].
[tex] \rm\int_{0}^{ \frac{\pi}{2} } \cot(x) \ln(\sec(x)) \\ [/tex]
Substitute y = tan(x) and dy = sec²(x) dx to transform the integral to
[tex]\displaystyle \int_0^{\frac\pi2} \cot(x) \ln(\sec(x)) \, dx = \frac12 \int_0^\infty \frac{\ln(1+y^2)}{y(1+y^2)} \, dy[/tex]
and we split the integral at y = 1.
Examining the one over [0, 1], expand into partial fractions :
[tex]\dfrac1{y(1+y^2)} = \dfrac1y - \dfrac y{1+y^2}[/tex]
Then
[tex]\displaystyle \int_0^1 \frac{\ln(1+y^2)}{y(1+y^2)} \, dy = \int_0^1 \frac{\ln(1+y^2)}y \, dy - \int_0^1 \frac{y \ln(1+y^2)}{1 + y^2} \, dy[/tex]
In the integral over [1, ∞), substitute y = 1/z :
[tex]\displaystyle \int_1^\infty \frac{\ln(1+y^2)}{y(1+y^2)} \, dy = \int_0^1 \frac{z \ln\left(1+\frac1{z^2}\right)}{1+z^2} \, dz \\\\ = \int_0^1 \frac{z \ln\left(1+z^2\right)}{1+z^2} \, dz - 2 \int_0^1 \frac{z \ln(z)}{1+z^2} \, dz[/tex]
Some terms cancel and we're left with
[tex]\displaystyle \int_0^\infty \frac{\ln(1+y^2)}{y(1+y^2)} \, dy = \frac12 \int_0^1 \frac{\ln(1+y^2)}y \, dy - \int_0^1 \frac{y \ln(y)}{1+y^2} \, dy[/tex]
Use the series expansions of ln(1 + y) and 1/(1 - y) - both are valid for |y| < 1.
[tex]\displaystyle \int_0^1 \frac{\ln(1+y^2)}y \, dy = - \sum_{n=1}^\infty \frac{(-1)^n}n \int_0^1 y^{2n-1} \, dy = -\frac12 \sum_{n=1}^\infty \frac{(-1)^n}{n^2} = \frac{\pi^2}{24}[/tex]
[tex]\displaystyle \int_0^1 \frac{y \ln(y)}{1+y^2} \, dy = \sum_{n=0}^\infty (-1)^n \int_0^1 y^{2n+1} \ln(y) \, dy = -\frac14 \sum_{n=0}^\infty \frac{(-1)^n}{(n+1)^2} = -\frac{\pi^2}{48}[/tex]
Putting everything together, we have
[tex]\displaystyle \int_0^{\frac\pi2} \cot(x) \ln(\sec(x)) \, dx = \frac12\times\frac{\pi^2}{24} - \left(- \frac{\pi^2}{48}\right) = \boxed{\frac{\pi^2}{24}}[/tex]