Wednesday

October 26, 2016
**Calculus**

A spotlight on the ground is shining on a wall 24\text{m} away. If a woman 2\text{m} tall walks from the spotlight toward the building at a speed of 0.6\text{m/s}, how fast is the length of her shadow on the building decreasing when she is 2\text{m} from the building?

*Tuesday, December 8, 2015 by Spencer*

**Calculus **

A home owner wants to fence in his yard of 600 sq. feet. Three sides are to be constructed with chain link fence at a cost of 3.25 per linear feet. The fourth side is to be constructed with a wood stockade fence at a cost of $5.45 per linear foot. A) what is a complete model ...

*Monday, December 7, 2015 by Jen*

**calculus**

Find the critical numbers x1 and x2 of y=(9x^2+3)/4x.

*Monday, December 7, 2015 by beth*

**calculus**

Use implicit differentiation to find the slope of the tangent line to the graph of 18*x^(1/2)+5y^(1/2)+14 at(81/324,1)

*Monday, December 7, 2015 by beth*

**calculus**

Find the derivative of y=(7x^(1/3))/(x^2+9)

*Monday, December 7, 2015 by beth*

**calculus**

Find the derivative of 4sinx(6cosx+9sinx) at x=¦Ð/6.

*Monday, December 7, 2015 by beth*

**Calculus**

Compute the surface area of revolution about the x-axis over the interval. y = x^2, [0, 4] Is it (pi/12)(65^2 - 65)^(3/2)?

*Monday, December 7, 2015 by Sanaya*

**Calculus**

Find the derivative of f(x)=(2x)^(1/2)ln(15x)

*Monday, December 7, 2015 by Erik*

**Calculus**

Find the derivative of y=(2*x^(3/2))/(x^2+5)

*Monday, December 7, 2015 by Erik*

**Calculus**

A baseball diamond is a square 90 ft on a side. A player runs from first base to second base at 15 ft/sec. At what rate is the player's distance from home base increasing when he is half way from first to second base?

*Monday, December 7, 2015 by Erik*

**calculus**

Sam has 1200 feet of fencing and wants to fence off a rectangular field that borders a straight river. He needs no fence along the river. Express the area of the field as a function of its dimension. Find the dimensions of the field that has the largest area.

*Monday, December 7, 2015 by hartati*

**Calculus**

How do I integrate sqrt of (1+e^(2x)) if doing u-sub.. u=sqrt of (1+e^(2x)) and ten using partial fraction...?

*Sunday, December 6, 2015 by Sanaya*

**Calculus**

Set up a double integral for calculating the flux of the vector field F⃗ (r⃗ )=r⃗ , where r⃗ =⟨x,y,z⟩, through the part of the upward oriented surface z=9(x^2+y^2) that lies above the disk x^2+y^2≤25.

*Sunday, December 6, 2015 by A*

**Calculus**

Find the surface area of the part of the sphere x2+y2+z2=81 that lies above the cone z=√(x2+y2)

*Sunday, December 6, 2015 by A*

**calculus**

what point of f(x)= e^(1-x^2) is concave down? I think it is 1/2 but I'm not sure

*Sunday, December 6, 2015 by tedd*

**calculus**

A satellite is free falling from a distance "d" of the surface of the moon with radius "r", with zero initial velocity. At what rate does the area of the portion of the moon visible to the satellite decrease at a time "t" after the free fall ...

*Saturday, December 5, 2015 by Steve*

**Calculus**

The approximate rate of change in the number of subscribers to wireless service is given by f’(t) = 1.498t + 1.626, where t represents the number of years since 1990. In 1992 (t = 2) there were approximately 8.893 million subscribers. Find the function that gives the ...

*Saturday, December 5, 2015 by Corey*

**Calculus**

Given dy/dt=4y and y(2)=400. Find y(7).

*Friday, December 4, 2015 by Erik*

**calculus**

The population of a culture of bacteria, P(t), where t is time in days, is growing at a rate that is proportional to the population itself and the growth rate is 0.3. The initial population is 40. (1) What is the population after 30 days? (2) How long does it take for the ...

*Friday, December 4, 2015 by E*

**Calculus**

The rate of change of the population of a small town is dP/dt=kP Where P is the population, t is the time in years and k is the growth rate. If P=20000 when t=3 and P=30000 when t=5, what is the population when t=10? Round your answer to the nearest integer.

*Friday, December 4, 2015 by E*

**Pre calculus**

Use the given conditions to write an equation for the line in point-slope form. Passing through (-5, -7) and (-8, -6)

*Thursday, December 3, 2015 by maddie*

**Pre calculus**

Find the domain of the function. f(x) = -2x + 4 A. (-∞, 0) u(0, ∞) B. (-∞, ∞) C. [-4, ∞) D. (0, ∞)

*Thursday, December 3, 2015 by lexi*

**Calculus**

At time t (in days), the size S of a population of butterflies is given by the formula s= 600/1+49(0.6)^t. When does the maximum growth rate occur?

*Thursday, December 3, 2015 by Leslie*

**Pre calculus**

Find the domain of the function. f(x) = -2x + 4 A. (-∞, 0) u(0, ∞) B. (-∞, ∞) C. [-4, ∞) D. (0, ∞)

*Thursday, December 3, 2015 by lexi*

**Pre calculus**

Find the domain of the function. f(x) = sqrt 6-x A. (-∞, 6) (6, ∞) B. (-∞, sqrt6 ) (sqrt 6 , ∞) C. (-∞, sqrt6] D. (-∞, 6]

*Thursday, December 3, 2015 by Alex*

**Pre-Calculus**

Draw the picture and find the area of the parcel of land. Circle your to partial areas and your total area. You start herman a corn and walk 300 yards due north. Then, you turn N 63 degrees E and walk 260 yards. Then, you turn S 55 degrees E and walk 240 yards. Then, you walk ...

*Thursday, December 3, 2015 by Ash*

**calculus**

A satellite is free falling from a distance (d) of the surface of the moon with radius (R), with zero initial velocity. At what rate does the area of the portion of the moon visible to the satellite decrease at a time (t) after the free fall starts? When is this rate maximum? ...

*Wednesday, December 2, 2015 by Saif*

**calculus**

Use the Trapezoidal Rule to approximate ¡Ò8 4 ln(x2+5) dx using n=3. Round your answer to the fourth decimal place.

*Wednesday, December 2, 2015 by beth*

**Pre-calculus**

You start from an acorn and walk 300 yards do north. Then, you turn N 63° E and walk 260 yards. Then, you turn S 55° E and walk 240 yards. Then you walk back to the little acorn.

*Tuesday, December 1, 2015 by Dee*

**Calculus 1**

The acceleration function (in m/s^2) and the initial velocity are given for a particle moving along a line. a(t)=t+4, v(0)=4, 0 ≤ t ≤ 11 (a) Find the velocity at time t. (b) Find the distance traveled during the give time interval.

*Tuesday, December 1, 2015 by TayB*

**Calculus III**

The surface x^2−y^2=36 can be described using spherical coordinates in the form ρ=g(θ,ϕ)=

*Monday, November 30, 2015 by Steven*

**calculus**

An open box is to be made out of a 10-inch by 14-inch piece of cardboard by cutting out squares of equal size from the four corners and bending up the sides. Find the dimensions of the resulting box that has the largest volume.

*Monday, November 30, 2015 by javy*

**Pre-Calculus**

f(x) = cos(x) on the interval [−2π, 2π] (a) Find the x-intercepts of the graph of y = f(x). (Enter your answers as a comma-separated list.) (b) Find the y-intercepts of the graph of y = f(x). (Enter your answers as a comma-separated list.) (c) Find the ...

*Sunday, November 29, 2015 by Sam*

**Calculus- Damon, Steve, Reiny**

I forgot to mention that I am trying to find sigma squared.. given that the mean is r and p(x)= (1/r)(e^(-x/r)) on the interval [0,infinity), where r>0.. note: sigma squared= integral sign (-inf, inf) (x-M)^2 p(x) dx i got (r^2 - 2r)^(1/2) for sigma, but my answer is wrong...

*Saturday, November 28, 2015 by Christina*

**Calculus**

I tried to integrate this: intergral sign with an interval from -inifinity to + infinity function: (x-r)^2 (1/r) (e^(-x/r)) with respect to dx..... I know that Steve set up the u-substitution but I seem to never arrive at an answer... It seems like I keep integrating and ...

*Saturday, November 28, 2015 by Christina*

**Calculus**

How do you integrate (x-r)^2 (1/r) (e^(-x/r)) from the interval negative infinity to positive infinity?

*Friday, November 27, 2015 by Sanaya*

**Calculus**

How do you integrate (x-r)^2 (1/r) (e^(-x/r)) from the interval negative infinity to positive infinity?

*Friday, November 27, 2015 by Christina*

**Math calculus **

The top and bottom margins of a poster are 8 cm and the side margins are each 8 cm. If the area of printed material on the poster is fixed at 382 square centimeters, find the dimensions of the poster with the smallest area?

*Friday, November 27, 2015 by MArıam *

**calculus**

integrate (e^t + e^-t)²

*Friday, November 27, 2015 by ligas*

**Integral Calculus**

Integrate (tan^-1 X)/(1+x²) dx please help, I don't know how to start this one

*Friday, November 27, 2015 by ligas*

**Integral Calculus**

Integrate (tan^-1 X)/(1+x²) dx please help, I don't know how to start this one

*Friday, November 27, 2015 by ligas*

**calculus**

integrate (e^t + e^-t)²

*Friday, November 27, 2015 by ligas*

**Pre Calculus HELP!?**

The length of a day in Philadelphia, Pennsylvania, is given by the sinusoidal function, f(t), which represents the number of hours of daylight t days into the year: f(t)= 10+2.8sin(2pi/365)*(t-1.35). How many hours of daylight are there on the 100th day of the year? Round the ...

*Thursday, November 26, 2015 by Ellie*

**Pre-Calculus HELP!!**

The length of a day in Philadelphia, Pennsylvania, is given by the sinusoidal function, f(t), which represents the number of hours of daylight t days into the year: f(x)=11+2.2sin(2pi/365)t-1.25).How many hours of daylight are there on the twelfth day of the year? Round the ...

*Thursday, November 26, 2015 by Ellie*

**calculus**

integrate (e^t + e^-t)²

*Wednesday, November 25, 2015 by ligas*

**Pre-Calculus HELP!**

Explain how the transformations of the functions f(x)=15sin(x) and f(x)=sin(x)+15 differ. I see that f(x)=sin(x)+15 experiences a vertical shift, but I am not sure about the transformation that f(x)=15sin(x) experiences. Thank you for your help!

*Wednesday, November 25, 2015 by Ellie*

**Calculus 1**

Use a graph to give a rough estimate of the area of the region that lies beneath the given curve. Then find the exact area. y = x^−3, 2 ≤ x ≤ 5

*Wednesday, November 25, 2015 by TayB*

**Calculus 1**

Use a graph to give a rough estimate of the area of the region that lies beneath the given curve. Then find the exact area. y = cube root(x) , 0 ≤ x ≤ 27

*Wednesday, November 25, 2015 by TayB*

**Calculus III**

Evaluate ∭W f(x,y,z)dV for the function f and region W specified: f(x,y,z) = 18(x+y) W: y≤ z≤x ; 0≤y≤x ; 0≤x≤1 ∭W (18(x+y))dV =

*Tuesday, November 24, 2015 by Steven*

**Calculus**

If f is an exponential function of the form f(x)=C times a^x with growth factor 5 and f(5)=14. What is f(6)? I know f(6) is 70 but how do you set up the equation to get 70?

*Tuesday, November 24, 2015 by Dale*

**calculus**

what are the inflection points of 5x^2-45/x^2-25

*Monday, November 23, 2015 by marissa*

**Calculus**

Integrate e^(-t/r) WITH RESPECT TO dt?

*Monday, November 23, 2015 by Sanaya*

**Calculus**

The amount remaining of a radioactive substance after t hours is given by A(t) = 100ekt. After 12 hours, the initial amount has decreased by 4%. How much remains after 48 hours? What is the half-life of the substance?

*Monday, November 23, 2015 by Bill*

**Pre-calculus**

Initially 600 milligrams of a radioactive substance was present. After 7 hours the mass had decreased by 3%. Construct an exponential model A(t) = A0ekt for the amount remaining of the decaying substance after t hours. Find the amount remaining after 24 hours.

*Monday, November 23, 2015 by Kim*

**Calculus**

find the maximum volume of a cylinder whose height and radius do not exceed a combined total of 12cm

*Monday, November 23, 2015 by Emma*

**Calculus**

Let f(x)=5x^(9/5)−45x^(4/5). Find the largest open interval(s) where f(x) increases.

*Monday, November 23, 2015 by Kevin*

**Calculus**

Calculate μ and σ, where σ is the standard deviation, defined by the following. σ^2 = integral between (−∞,∞) (x-μ)^2 p(x) dx The smaller the value of σ the more tightly clustered are the values of the random variable X about the...

*Sunday, November 22, 2015 by Christina*

**Calculus**

How do you integrate e^(-t/r) dt?

*Sunday, November 22, 2015 by Sanaya*

**Calculus**

Calculate μ and σ, where σ is the standard deviation, defined by the following. σ^2 = integral between (−∞,∞) (x-μ)^2 p(x) dx The smaller the value of σ the more tightly clustered are the values of the random variable X about the...

*Sunday, November 22, 2015 by Anonymous*

**Calculus**

How do you integrate e^(-t/r)?

*Sunday, November 22, 2015 by Sanaya*

**Calculus**

Integrate x/(6x-5) dx The answer is 1/6 x + 5/36 ln abs (36x-30) + C... But I don't understand why it is 5/36 times ln.. I thought that when you factored out the 5 you would get 5 times ln abs (36x-30)..

*Saturday, November 21, 2015 by Sanaya*

**Calculus**

A window is designed to be the area between a parabolic section and a straight base. The height is 0.640 m and the base is 1.60 m. What is the area of the window?

*Saturday, November 21, 2015 by Anonymous*

**Calculus**

Calculate integral [0, infinity) xe^(-x) dx

*Saturday, November 21, 2015 by Sanaya*

**Calculus**

Find the solution t the differential equation dz/dt = 2te^z that passes through the origin. My answer is -In (1-t^2), but my answer is populating as incorrect. Can someone help please?

*Friday, November 20, 2015 by Latoya*

**Calculus**

Solve the initial value problem 2y" + 5y' - 3y = 0 y(0) =7, y'(0) = 7 Can someone please help. The answer I came up with is 35 exp(-x) - 28 exp(-3x/2), but my answer is wrong.

*Friday, November 20, 2015 by Latoya*

**Calculus**

For the vector field G⃗ =(yexy+3cos(3x+y))i⃗ +(xexy+cos(3x+y))j⃗ , find the line integral of G⃗ along the curve C from the origin along the x-axis to the point (3,0) and then counterclockwise around the circumference of the circle x2+y2=9 to the point (...

*Friday, November 20, 2015 by A*

**Calculus**

Integral sign 8x/(x-1) dx Is it 8x+8ln abs (x-1)+C ?

*Thursday, November 19, 2015 by Sanaya*

**Calculus**

Evaluate the integral. Problem#1 Integral sign 4dx/[(x+3)(x^2 +3x) Does it matter where A, B, and C is placed over. Is there a particular order? Is it ..... (A/x)+(B/(x+3))+(c/(x+3)^2=4 Or ... (A/x+3)+(B/x)+(C/(x+3)^2)=4 I am confused because I get different answers each time ...

*Thursday, November 19, 2015 by Sanaya*

**Calculus**

Evaluate using long division. The integral of x/6x-5 dx How do I divide this?

*Thursday, November 19, 2015 by Sanaya*

**Calculus 1 **

Find each limit: (a) lim x->1 (ln(x)+2x-2)/(x^2-1) (b) lim x->infinity (x^2)/(e^x)

*Thursday, November 19, 2015 by TayB*

**Calculus 1 **

Find the local maximum and minimum for the function f(x)=2x^3-3x^2-120x+10

*Thursday, November 19, 2015 by TayB*

**Calculus III**

Use symmetry to evaluate the double integral ∫∫R(10+x^2⋅y^5) dA, R=[0, 6]×[−4, 4]. (Give your answer as an exact number.) ∫∫R(10+x^2⋅y^5) dA=

*Wednesday, November 18, 2015 by Stevo*

**Pre Calculus 1**

thirty percent of a radioactive substance decays in four years. assuming the decay is exponential, find the half life of the substance. the beginning of 1975 the population of a country was 40 million and growing at a rate of 3% per year. Assume that the growth is exponential...

*Wednesday, November 18, 2015 by Yasmine*

**Business Calculus**

The skeleton has lost 56 percent of their carbon-14. The constant proportionality is approximately k=0.000124. Estimate the age of the bones.

*Wednesday, November 18, 2015 by Amy*

**Calculus**

Evaluate using long division. The integral of x/6x-5 dx How do I divide this?

*Tuesday, November 17, 2015 by Rucha*

**math (Calculus III)**

In this example we should use the beta function. But I'm a bit lost, because I don't know how to change the limits of the integral to fit the one that is needed when using B-function. The problem goes like this: integrate cos^7(x) dx, limits of the integral are from 0 ...

*Tuesday, November 17, 2015 by Marie*

**Calculus**

Find the first partial derivatives and evaluate each at the given point. Function w = sqrt(5x^2 + y^2 − 4z^2) Point (2, −4, 2) wx(2, −4, 2) = wy(2, −4, 2) = wz(2, −4, 2) =

*Tuesday, November 17, 2015 by Calculus Help *

**Calculus**

Find the four second partial derivatives and evaluate each at the given point. Function f(x, y) = x^3 + 2xy^3 − 9y Point (9, 2) fxx(9, 2) = fxy(9, 2) = fyx(9, 2) = fyy(9, 2) =

*Tuesday, November 17, 2015 by Calculus Help *

**Calculus**

Find the first partial derivatives and evaluate each at the given point. Function w = 2x^2y − 6xyz + 10yz^2 Point (2, 5, −3) wx(2, 5, −3) = wy(2, 5, −3) = wz(2, 5, −3) =

*Tuesday, November 17, 2015 by akash*

**Calculus**

A pharmaceutical corporation has two locations that produce the same over-the-counter medicine. If x1 and x2 are the numbers of units produced at location 1 and location 2, respectively, then the total revenue for the product is given by R = 700x1 + 700x2 − 2x1^2 −...

*Tuesday, November 17, 2015 by akash*

**calculus**

You have been hired by a farmer to design a fenced-in rectangular enclosure for emus. The emus will require 720 square feet of area in which to roam, and the fence will cost 20 dollars per foot. The rectangular area will adjoin an existing wall, so a fence is only needed on ...

*Tuesday, November 17, 2015 by carl*

**Calculus**

A tennis ball is dropped from a height of 32 feet, rebounding to 1/2 its former height with each bounce. How far will the ball have traveled VERTICALLY when it comes to a rest?

*Monday, November 16, 2015 by Sean*

**Pre-Calculus**

Big Bob is trying to shape up for the summer. He begins on the first day of his exercise program with 3 sit ups. Each day he will do 4 more sit ups than the day before. On what day will Big Bob do 115 sit ups?

*Monday, November 16, 2015 by Claire*

**Calculus**

Partial fractions of (2x^2 +8x+24)/(x+2)^2 (x^2 +4) I see a repeated quadratic and an irreducible quadratic..

*Sunday, November 15, 2015 by Rucha*

**pre calculus**

find 2 solutions of tan θ=.6524 in both degrees and radians. I know the answer are 33.12 degrees/.578 radians and 213.12 degrees/3.72 radians, but how do you find this? Thanks!!!!

*Sunday, November 15, 2015 by elle*

**Calculus 1**

Use Newton's method to approximate the indicated root of the equation correct to six decimal places. The root of x^4 − 2x^3 + 5x^2 − 5 = 0 in the interval [1, 2]

*Sunday, November 15, 2015 by TayB*

**Calculus 1**

Consider the function below. f(x)= (x^2)/((x-4)^2) Find the interval where the function is concave up. (Enter your answer using interval notation.) Find the intervals where the function is concave down. (Enter your answers using interval notation.) For interval where the ...

*Sunday, November 15, 2015 by TayB*

**Calculus 1**

Find the absolute minimum and absolute maximum values of f on the given interval. f(t) = 16 cos t + 8 sin 2t, [0, π/2]

*Saturday, November 14, 2015 by TayB*

**calculus**

Use the Left and Right Riemann Sums with 100 rectangle to estimate the (signed) area under the curve of y=−2x+1 on the interval [0,50]. Write your answer using the sigma notation.

*Friday, November 13, 2015 by Mark*

**Calculus**

Use the Left and Right Riemann Sums with 80 rectangle to estimate the (signed) area under the curve of y=e^(3x)−5 on the interval of [10,20]. Write your answer using the sigma notation

*Friday, November 13, 2015 by Mark*

**Calculus 1**

Use Newton's method to find the coordinates, correct to six decimal places, of the point on the parabola y = (x − 5)^2 that is closest to the origin.

*Friday, November 13, 2015 by TayB*

**Calculus 1**

Use Newton's method to find all roots of the equation correct to six decimal places. (Enter your answers as a comma-separated list.) 7/x = 1 + x^3

*Friday, November 13, 2015 by TayB*

**Calculus 1**

Use Newton's method to find the coordinates, correct to six decimal places, of the point on the parabola y = (x − 5)^2 that is closest to the origin.

*Friday, November 13, 2015 by TayB*

**Calculus 1**

Of the infinitely many lines that are tangent to the curve y = −4 sin x and pass through the origin, there is one that has the largest slope. Use Newton's method to find the slope of that line correct to six decimal places.

*Friday, November 13, 2015 by TayB*

**Pre-Calculus**

1) For tax purposes a manufacturer is allowed to depreciate the value of a machine by 10% each year. If the original value of the machine was $10,000, what would be its value for tax purposes at the end of 6 years. (Assume the depreciation is computed at the end of each year...

*Thursday, November 12, 2015 by Anon*

**Integral Calculus - Series**

Find if series is convergent or divergent. Series from n=2 to infinity (4n+7)/(3n^3 -8n)

*Thursday, November 12, 2015 by John*

**Calculus 1**

Of the infinitely many lines that are tangent to the curve y = −4 sin x and pass through the origin, there is one that has the largest slope. Use Newton's method to find the slope of that line correct to six decimal places.

*Thursday, November 12, 2015 by TayB*

**Calculus**

Find the area of the unbounded shaded region. Y= 7/ SQRT (7-X)

*Thursday, November 12, 2015 by akash*

**Calculus**

A professional athlete signs a four-year contract in which the earnings can be modeled by c = 300,000 + 750,000t, where t represents the year. (a) Find the actual value of the athlete's contract. =7200000 (b) Assuming an annual inflation rate of 4%, what is the present ...

*Thursday, November 12, 2015 by akash*

**Calculus**

Find the area of the unbounded shaded region. Y= 7/ SQRT 7-X

*Thursday, November 12, 2015 by Please Help Me ! *