Monday

July 27, 2015

July 27, 2015

**Calculus**

Can someone show how to solve this problem Two vertical towers of heights 60 ft and 80 ft stand on level ground, with their bases 100 ft apart. A cable that is stretched from the top of one pole to some point on the ground between the poles, and then to the top of the other ...
*Monday, July 27, 2015 by Hank*

**pre-calculus **

which expression is equivalent to (sinx+1)(sinx-1)? A.) COS^2X B.) -COS^2X C.) COS^2X+1 D.) COS^2X-1 E.) -COS^2X+1
*Monday, July 27, 2015 by Daisy*

**pre-calculus **

find the exact value of sin 112.5 in fraction form
*Monday, July 27, 2015 by Daisy*

**pre-calculus **

which of the following is a solution to 3tan^3x=tanx? A.) 60 degrees B.) 120 degrees c.)150 degrees D.)240 degrees E.)300 degrees
*Monday, July 27, 2015 by Daisy*

**pre-calculus **

Which of the following is NOT a solution to cos^2x=3sin^2x? A.) 30 degrees B.) 60 degrees C.) 150 degrees D.)210 degrees E.)330 degrees
*Monday, July 27, 2015 by Daisy*

**pre-calculus **

What is the exact value of sin 225
*Monday, July 27, 2015 by Daisy*

**calculus problem I have tried 100 times**

A tank in the shape of an inverted right circular cone has height 5 meters and radius 4 meters. It is filled with 2 meters of hot chocolate. Find the work required to empty the tank by pumping the hot chocolate over the top of the tank. The density of hot chocolate is δ=...
*Sunday, July 26, 2015 by Anonymous*

**Calculus**

My teacher wants me to use this formula for half life question C(t) = Ce^-kt but i used a different formula plz help. the question is: A radioactive isotope has a half life of 30 years. If we started off with 10 mg of this isotope 12 years ago: a) Find and expression for the ...
*Sunday, July 26, 2015 by max*

**Calculus**

Show that the limit as h approaches 0 of (e^h-1 ) all over h = ln e = 1 using at least two numerical examples.
*Sunday, July 26, 2015 by Jonathan*

**Calculus**

Find the derivative of the following functions using the f prime of x = the limit as h approaches 0 of f(x+h) – f(x) all over h a)ƒ(x) = x2 + 5^x b)ƒ(x)= 1/2^x
*Sunday, July 26, 2015 by Jonathan*

**Integral calculus**

The length of each leg of an isosceles right triangle is increase at the rate of 2 mm/s. How fast is the hypotenuse increasing at the moment when each leg is 10 mm?
*Saturday, July 25, 2015 by paula*

**Calculus**

Can someone explain how cos(X)/ square root (sin (X)) is 2 square root sin(x) +c Thanks!
*Thursday, July 23, 2015 by John*

**Calculus**

Givenƒ(x) = ex, verify that lim h->0 (e^x+h - e^h)/h + e^x and explain how this illustrates that ƒ′(x) = ln e • ƒ(x) = ƒ(x)
*Wednesday, July 22, 2015 by Jonathan*

**calculus**

find volumes of solids generated by revolving the regions bounded by the graphs of the equations about the given lines. y=square root of x y=0 x=3
*Wednesday, July 22, 2015 by Pam*

**calculus**

A cylindrical tank is to have a capacity of 1000 m³. It is to fit into a foundry that is 12 m wide with a height of 11 m. The base of the tank will cost half as much as the top. The metal for the side of the tank will cost four fifths as much as the top. An equation that ...
*Wednesday, July 22, 2015 by nal*

**Calculus**

(0.064)(2*pi*h)+(0.064)*4*pi*r=z*2*pi*r*h (0.064)2*pi*r=z*pi*r^2 pi*r^2*h=1567.8 Find r,h,z
*Wednesday, July 22, 2015 by Mars*

**calculus**

how to find surface area of a cylinder with respect to r(radius) and h(height)?
*Tuesday, July 21, 2015 by RR*

**calculus**

Sketch the region in the first quadrant enclosed by y=6/x, y=2x, and y=.5x. Decide whether to integrate with respect to x or y. Then find the area of the region. need final area as answer please, and step would be helpful also if you can post.
*Sunday, July 19, 2015 by Nick*

**Calculus**

Can someone show how this question is solved. Consider the curve given by the equation 2y^3 + y^2 - y^5 = x^4 -2x^3 +x^2 Find all points at which the tangent line to the curve is horizontal or vertical. Thanks!
*Saturday, July 18, 2015 by Henry*

**calculus**

Sketch the region in the first quadrant enclosed by y=6/x, y=2x, and y=12x. Decide whether to integrate with respect to x or y. Then find the area of the region.
*Saturday, July 18, 2015 by Nick*

**calculus**

The temperature of a hard boiled egg varies according to Newton's Law of Cooling: dT dt equals negative k times the quantity T minus A, where T is the temperature of the egg, A is the room temperature, and k is a positive constant. If the egg cools from 100°C to 90°...
*Friday, July 17, 2015 by Anonymous*

**calculus**

Find the particular solution to y ′ = sin(x) given the general solution is y = C − cos(x) and the initial condition y(pi/2)=1
*Friday, July 17, 2015 by Anonymous*

**calculus**

The rate of decay in the mass, M, of a radioactive substance is given by the differential equation dM dt equals negative 1 times k times M, where k is a positive constant. If the initial mass was 100g, then find the expression for the mass, M, at any time t.
*Friday, July 17, 2015 by Anonymous*

**calculus**

Newton’s law of cooling states that the rate of cooling of an object is proportional to the temperature difference between the object and its surroundings. So the rate of cooling for a bottle of lemonade at a room temperature of 75°F which is placed into a ...
*Thursday, July 16, 2015 by Anonymous*

**Calculus**

My question is finding the derivitive of y=((x+λ)^4)/(x^4+λ^4). I distributed the exponent in the numerator, but I don't know if that's right. Rewritten as y=(x^4+λ^4)/(x^4+λ^4). I found the derivitive and multiplied accordingly, as ((4x^3+4λ^3...
*Wednesday, July 15, 2015 by Jessica*

**Calculus**

So, I have a homework question on The Quotient Rule (taking derivitives) and I would like to know if I did it right. Calculate: y=(1/sqrt(x))-(1/(5th root of x^3). My 1st step was to change the sqrt to x^1/2, and the 5th root to x^1/5+^3. So then I got y=(1/x^1/2)-(1/x^16/5). ...
*Wednesday, July 15, 2015 by Jessica*

**Calculus Partial Derivatives**

Verify that the sum of three quantities x, y, and z, whose product is a constant k, is maximum when these three quantities are equal.
*Wednesday, July 15, 2015 by Anonymous*

**calculus**

Sketch the region enclosed by the given curves. Decide whether to integrate with respect to x or y. Then find the area of the region. y=3+√X, y=3+1/5x What is the area?
*Tuesday, July 14, 2015 by Nick*

**Calculus**

y = g(x) = cos(x) Can someone show how to estimate g'(pi/2) using the limit definition of the derivative and different values of h. Thanks!
*Sunday, July 12, 2015 by Henry*

**Calculus Partial Derivatives**

Problem: Find dimensions of a box that provide the greatest volume when the length plus the girth cannot exceed six feet. I tried 2w+2h+l=6, l=6-2w-2h, but couldn't get to w=1, h=1, l=2, which is the correct answer.
*Friday, July 10, 2015 by Anonymous*

**Calculus Partial Derivatives**

y=F(x+at) + f(x-at) y=F(w) + f(v) (w=x+at, v=x-at) don't see how to get from here to partial derivative y with respect to t = F"(w)a^2 + f"(v)a^2
*Thursday, July 9, 2015 by Anonymous*

**Calculus**

Can someone provide a function that satisfies all of the following: • p(−1) = 3 and lim x→−1 p(x) = 2 • p(0) = 1 and p'(0) = 0 • lim x→1 p(x) = p(1) and p'(1) does not exist Thanks!
*Wednesday, July 8, 2015 by Henry*

**Calculus**

1. Provide an example of a function f that is continuous at a = 2 but not differentiable at a = 2. 2. Provide an example of a function g that is differentiable at a = 3 but does not have a limit at a = 3. Thanks!
*Wednesday, July 8, 2015 by Andy*

**Calculus**

Please simplify the expression: 2log(base 4)9 - log(base 2)3
*Wednesday, July 8, 2015 by Alisha*

**Calculus**

Simplify: (5x^3 + x^2 - x)/ (3x)
*Wednesday, July 8, 2015 by Mona*

**Calculus**

I have a graph of f(x) which I cant post here, but would like some help with concepts. lim f(x) = L x->a I already found the limit for different values of a. Now I need to find the value of f(a) at each point. So is f(a) = lim f(x) x->a So f(a) is just the same value of ...
*Tuesday, July 7, 2015 by George*

**Calculus**

Determine over what interval(s) is the function y=4x-6arctan(x) is concave up/concave down I took the second derivative and ended up with x=0. I do not believe I did this right. IF I happen to be right, wouldn't our answer just be undefined, rather than having intervals ...
*Tuesday, July 7, 2015 by John*

**Calculus AB**

Find the limit as x->infinity of ((3x+2)/(3x+4))^(3x+1)
*Tuesday, July 7, 2015 by Patricia*

**Calculus**

Find max or min: y = x * cosx
*Tuesday, July 7, 2015 by Anonymous*

**Calculus**

log (base 3) x^2 = 2log(base 3)4-4log(base 3)5 And I need to solve for x.
*Monday, July 6, 2015 by Mona*

**Calculus**

The velocity of a ball that has been tossed vertically in the air is given by v(t) = 16 − 32t, where v is measured in feet per second, and t is measured in seconds. The ball is in the air from t = 0 until t = 2. Determine the value of v'(1). What are the units on the...
*Monday, July 6, 2015 by George*

**pre calculus **

32% of a particular radioactive substance disappears in 227 years. Part 1: Find the decay constant. Your answer must be correct to five decimal places. Part 2: Determine the time T in years required for 93% of the substance to disapper. Your answer must be correct to two ...
*Monday, July 6, 2015 by Morgan*

**Calculus **

A particle moves on a vertical line so that its coordinate at time t is 3 y = t − 12t+ 3, t≥ 0 . When is the particle moving upward and when is it moving downward? Find the distance that the particle travels in the first 3 seconds. I got that t=2 and t=-2 and its ...
*Sunday, July 5, 2015 by John*

**Calculus**

How do the constants 5, 4, and 12 in f(x) = 5x^2 - 4x + 12, affect the derivative? Thanks!
*Sunday, July 5, 2015 by Fred*

**calculus**

radioactive Carbon 14 in a dead organism decays according to the equation A=A e^.000124t where t is in years and A0 is the amount at t=0. Estimate the age of a skull uncovered in an archeological site if 10% of the original Carbon 14 is still present.
*Friday, July 3, 2015 by veronica*

**Calculus Minimum**

Problem: Find minimum?maximum for: y=xa^(1/x) Ans given: X=ln(a) (min) Can't get to it.
*Thursday, July 2, 2015 by Anonymous*

**Calculus**

Find the limit of cosx/(1-sinx) as x->(pi/2) from + side
*Thursday, July 2, 2015 by Patricia*

**calculus**

calculate the largest area possible that can be made by a 15 meter long wire that will be bent to form a closed plane area. No figure given
*Thursday, July 2, 2015 by Jhun*

**calculus**

Car A is 30 mi apart from car b. Car A moves 30 mph due east at the same time car b moves 30 degrees south of east. how fast is the distance between them changing after an hour.
*Thursday, July 2, 2015 by Jhun*

**calculus**

p=-1/5x+200 Cost of a Commodity. The price p, in dollars, of a certain commodity and the quantity x sold. Obey the demand equation. p= -1/5x+200
*Wednesday, July 1, 2015 by Anonymous-2*

**Calculus Derivative**

Find derivative: y= e^(x^x)
*Wednesday, July 1, 2015 by Anonymous*

**Differential calculus**

The voltage across the plates of a capacitor at any time t seconds is given by V=Ve -t/CR, where V,C and r are constants. Given V = 300 Volts, C =0.12*10-6 F and R = 4*10 6 ohms Find the initial rate of change of voltage and the rate of change of voltage after 0.5 seconds
*Tuesday, June 30, 2015 by lee*

**calculus**

Find the complex zeros of the polynomial function. F(x)=5x^4-16x^3-22x^2+200x-39
*Tuesday, June 30, 2015 by Anonymous-2*

**Calculus**

A rectangular page is to contain 72 square inches of print. The page has to have a 4 inch margin on top and at the bottom and a 2 inch margin on each side. Find the dimensions of the page that minimize the amount of paper used.
*Monday, June 29, 2015 by Uri*

**calculus**

Cost of a Commodity. The price p, in dollars, of a certain commodity and the quantity x sold. Obey the demand equation. p= -1/5x+200
*Sunday, June 28, 2015 by Anonymous-2*

**Calculus Partial Fraction**

Sorry. The problem should have been: (x^2)/(x^3-8)(x-2)
*Sunday, June 28, 2015 by Anonymous*

**Calculus Partial Fraction**

(x^2)/(x^3)(x-2)
*Sunday, June 28, 2015 by Anonymous*

**Calculus, derivatives**

Derivative of y=(a^x)+(x^a). Show steps, please.
*Saturday, June 27, 2015 by Walt*

**Pre Calculus**

Let θ be an angle in quadrant IV such that cosθ = 4/9. Find the exact values of csc θ and cot θ. I am just completely lost! Thanks!
*Friday, June 26, 2015 by Anonymous*

**Calculus**

Demand Equation. The price(in dollars),and the quantity x sold of a certain product, obey the demand equation. I can't figure out what price the company should charge to maximize revenue p=-1/10x+150 R=p*x R=((-1/10)*x+150)*x R=(-1/10)*x^2+150x y=ax^2+b*x+c a=-1/10 b=150 c...
*Monday, June 22, 2015 by Anonymous-1*

**Calculus(math)**

A particle is moving on a straight line in such a way that its velocity v is given by v(t)=2t+1 for 0≤t≤5 where t is measured in seconds and v in meters per second. What is the total distance traveled (in meters) by the particle between times t=0 seconds and t=5 ...
*Sunday, June 21, 2015 by Alice*

**calculus**

The base of a solid is the circle x2 + y2 = 9. Cross sections of the solid perpendicular to the x-axis are equilateral triangles. What is the volume, in cubic units, of the solid?
*Sunday, June 21, 2015 by Anonymous*

**Calculus AB**

Gateway Arch in St. Louis was constructed using the equation y=211.49-20.96cosh(0.03291765x) where |x|<=91.20 a) what is the height at its center in meters b) At what points is height 70m (2 values of x) c) what is the slope of arch at points in part b
*Sunday, June 21, 2015 by Patricia*

**Calculus**

Using a graphing calculator and the concept of differentials determine the values for x when 1/(1+3x)^5 is approx = to (1-15x) within .01
*Sunday, June 21, 2015 by Greg*

**Calculus**

Ferris wheel has radius of 26m. At what rate is the rider's height increasing, when rider is 25 m from ground.
*Sunday, June 21, 2015 by Mike*

**pre-calculus**

Steve, The following rational function describes concentration in blood of a certain medicine taken once depending on time, find: A. the horizontal asymptote B. the vertical asymptote C. describe their possible meaning ( I only need help with C). f(x)=x/x^2-100 Sharon
*Saturday, June 20, 2015 by Sharon*

**pre-calculus**

The following rational function describes concentration in blood of a certain medicine taken once depending on time, find: A. the horizontal asymptote B. the vertical asymptote C. describe their possible meaning ( I only need help with C
*Saturday, June 20, 2015 by Sharon*

**Calculus**

Using differentials find dy and delta y when y=7/x and dx=delta x =1
*Saturday, June 20, 2015 by Pat*

**Calculus**

two sides of triangle are 10m and 19m and the angle between them is increasing at a rate of 2 degrees per minute. How fast is the third side changing when the angle between them is 60 degrees
*Saturday, June 20, 2015 by Pat*

**Calculus**

A 0.9 ml dose of a drug is injected into a patient steadily for half a second. At the end of this time, the quantity, Q, of the drug in the body starts to decay exponentially at a continuous rate of 0.4% per second. Using formulas, express Q as a continuous function of time, t...
*Thursday, June 18, 2015 by Devon*

**calculus**

The following rational function describes concentration in blood of a certain medicine taken once depending on time, find: A.the horizontal asymptote(s) B.the vertical asymptote(s) C. describe their possible meanings Horizontal asymptote is y=-100 vertical asymptotes are x=-10...
*Wednesday, June 17, 2015 by Sharon*

**Calculus**

One side of a rectangular animal pen is to be formed by the side of a barn. If you have enough material to build a total of 34 feet of fence, find the maximum area than can be enclosed
*Wednesday, June 17, 2015 by Bella*

**Calculus**

Okay, so I worked out 17 = T(10) = 2 + 23e ^10k 15/23 = e^10k k= 1/10ln(15/23) k = - 0.043 But when I do this equation 17 = T(30) = 2 + 23e^30k 15/23 = e^30k k = 1/30ln(15/23) k = -0.142 But the answer is apparently 8.38? Can someone please help. I think I'm getting too ...
*Wednesday, June 17, 2015 by Anonymous*

**pre-calculus 11 **

I have a question that two ski decide to have a race. I need show a graph of height versus time of the two skiers going over a jump. I am assuming that both skiers graphs would be parabola's and have a maximum height with both graphs opening downward.
*Tuesday, June 16, 2015 by george *

**pre-calculus 11**

The infinite series 1+3x +9x^2 +27x^3+.. has a sum of 4.The value of x is? so if 1/1-r I substitute 1/1-3x =4 so x=1/4 if someone could confirm that my answer is correct? thanks so much
*Tuesday, June 16, 2015 by george *

**pre-calculus 11 **

The question is the roundtrip flight from Edmonton to Toronto covers a distance of 5400km in 7.6 hours. The speed from Edmonton to Toronto was 95 km/h faster than the speed from Toronto to Edmonton. What was the speed of the plane from Toronto to Edmonton? If i set up my ...
*Tuesday, June 16, 2015 by george *

**pre-calculus 11 **

-x/(x-3) + 2x/(x+2) (x-1) x (x-2) (x+2)/(x-3)(x-3) my question is should i multiply first and then do the adding or subtracting thru a LCD or should i do the adding first?
*Tuesday, June 16, 2015 by george *

**pre-calculus 11 **

a launch window of 8:00 to 12:00. If t represents the launch time then what is an acceptable range of values for launch times? My thoughts are on this is that the scientist have a window of 4 hours which can include 8:00 and 12:00 but cannot exceed them. So time could be ...
*Tuesday, June 16, 2015 by george *

**Calculus**

On the closed interval, [0, 2*pi], find the absolute maximum of the function f(x)= sin^2(x)
*Monday, June 15, 2015 by Alex*

**calculus**

Find the distance, in feet, a particle travels in its first 4 seconds of travel, if it moves according to the velocity equation v(t)= −t2 + 4 (in feet/sec).
*Monday, June 15, 2015 by Anonymous*

**calculus**

A girls throws a tennis ball straight into the air with a velocity of 64 feet/sec. If acceleration due to gravity is −32 ft/sec2, how many seconds after it leaves the girl's hand will it take the ball to reach its highest point? Assume the position at time t = 0 is 0...
*Monday, June 15, 2015 by Anonymous*

**Calculus**

A ladder 30 ft. long is leaning up against a building. If the top of the ladder is being pulled up the wall of the building at a rate of 1.5 feet per minute, find the rate at which the base of the ladder is moving toward the building when it is 18 feet from the wall.
*Monday, June 15, 2015 by Alex*

**pre-calculus 11**

an object has a mass of m= 3x/4x^2 and density of d=x-1/2^2 where ve m/d and state any restrictions on the variable. So this simplifies to v=3x/2x-2 my question is the restriction i have found is x cannot be 1 which would make the denominator zero. Do I have to be concerned ...
*Monday, June 15, 2015 by George*

**pre-calculus 11 **

I have the question y=-|x^2 -9| I am asked for the piecewise function. I have written y={-x^2 +9 if x less than equal to -3} { x^2 -9 if x is greater than equal to 3} I am wondering if I have my are signs backwards.My reasons for choosing the signs I have is if I plug a ...
*Sunday, June 14, 2015 by george *

**pre-calculus 11 **

I am asked to solve the absolute value equation of |1/2x +1| =x+1 graphically. I can solve this algebraically and consider two cases for the absolute value one being positive and the other negative. I know this will be a straight line and when I solved it algebraically x=0 the...
*Sunday, June 14, 2015 by george *

**Calculus **

for a normal curve what percentage of values falls beyond two standard deviations from the mean
*Sunday, June 14, 2015 by Jonah*

**Calculus**

A strong swimmer is one mile off shore at point P. Assume that he swims at the rate of 3 mile per hour and walk at the rate of 5 miles per hour. If he swims in a straight line from P to R and then walks from R to Q, how far should R be from Q in order that he arrives at Q in ...
*Saturday, June 13, 2015 by Selena*

**Calculus**

A wire 17 inches long is cut into two pieces. One piece is bent to form a square and the other is bent to form a rectangle that is twice as wide as it is high. How should the wire be cut in order to minimize the total area of the square and rectangle?
*Saturday, June 13, 2015 by Selena*

**Pre-Calculus **

Can someone please help me with this question? Show that x=a cos t+h, y=b sin t+k; 0<t<2pi (greater than and EQUAL to) are parametric equations of an ellipse with center (h,k) and axes of lengths 2a and 2b. Thank you so much!
*Saturday, June 13, 2015 by Anonymous*

**Calculus**

Find the integral of x/cos^2(x^2)dx The answer is 1/2 tan (x^2) + C. Where does the 1/2 come from?
*Thursday, June 11, 2015 by Anonymous*

**Pre Calculus**

a biologist has three salt solutions: some 5% solution, some 15% solution, and some 25% solution. She needs to mix some of each to get 50 liters of 20% solution. She wants to use twice as much of the 5% solution as the 15% solution. How much of each solution should she use? I...
*Wednesday, June 10, 2015 by Jaden*

**Calculus 1**

The height (in meters) of a projectile shot vertically upward from a point 3 m above ground level with an initial velocity of 21.5 m/s is h = 3 + 21.5t − 4.9t2 after t seconds. (Round your answers to two decimal places.) a. When does it hit the ground? I set the equation...
*Wednesday, June 10, 2015 by Laurel*

**Finite Math**

Fifty percent of students enrolled in calculus class have previously taken pre-calculus. Thirty percent of these students received an A for the calculus class, whereas twenty percent of the other students received an A for calculus. Find the probability that a student selected...
*Wednesday, June 10, 2015 by Nikole*

**pre-calculus 11 **

I have f(x) + 1/ x-c this is the question and I am told for the function with a vertical asymptote at x=1 Mr. Reimy was kind enough to provide this information comparing it to y = 1/x for the first interpretation the graph of y = 1/x would simply be translated vertically by c ...
*Wednesday, June 10, 2015 by george *

**pre-calculus 11 **

I have the question what is the equation of the function in the form f(x) = 1/x-c for the function with a vertical asymptote at x=1? sketch the graph. I am uncertain how I plug this into a graphing calculator. Could I substitute 1 for x and then put an x in for c to input this...
*Wednesday, June 10, 2015 by george *

**pre-calculus 11 **

I am asked to solve the absolute value equation of |1/2x +1| =x+1 graphically. I can solve this algebraically and consider two cases for the absolute value one being positive and the other negative. I know this will be a straight line and when I solved it algebraically x=0 the...
*Wednesday, June 10, 2015 by george *

**pre-calculus 11 **

I have the question y=-|x^2 -9| I am asked for the piecewise function. I have written y={-x^2 +9 if x less than equal to -3} { x^2 -9 if x is greater than equal to 3} I am wondering if I have my are signs backwards.My reasons for choosing the signs I have is if I plug a ...
*Wednesday, June 10, 2015 by george *

**Pre calculus/ Advanced Functions**

Samuel is investigating the rate of change of the function f(x) = cos x on the interval xE[0, 2pi]. He notices that the graph of f(x) passes through the x-axis at pi/2. He also determines the instantaneous rate of change at x = 0, pi and 2pi by inspection. Based on this ...
*Tuesday, June 9, 2015 by Anonymous*

**pre-calculus 11**

abs x^2/2 -1 =x+3 solve algebraically so if I divide thru by 2 i get x^2 -2= 2x+3 simplifying x^2-2x-5 =0 solve by quadratic formula to get =3.449 and -0.445 both of which are extraneous roots if I take negative then I get -x^2 +2=2x+6 simplify to x^2 +2x +4 if taking using ...
*Tuesday, June 9, 2015 by george *

**Calculus 1**

True or false. Explain. The line x=1 is a vertical asymptote of f(x)=(x^2+x-2)/(x^2-1)
*Tuesday, June 9, 2015 by TayB*