Sunday
May 1, 2016

# Posts by alex

Total # Posts: 3,420

Calculus
A cardioid r=1+cos(theta) A circle r=3*cos(theta) a) Define the domain of the region enclosed inside both the cardioid and the circle. b) Use polar coordinates to calculate the area. (We can use symmetry about x-axis)
May 1, 2016

Physics
Three objects are connceted by a massless wires over a frictionless pulley. The right side of the pulley wire is connected to a 15kg block and right below that is a 10kg block on the bottom of the wire. The tension in the wire connecting the 10kg and 15kg objects is measured ...
April 30, 2016

Physics
A 100 kg block is hanging from a frictionless pulley with another block of unknown mass on the other side of the pulley. It is released from a height of 1 meter above the ground. It then takes 0.9 seconds to reach the ground. What is the weight of the other mass?
April 30, 2016

Physics
Thanks a bunch Bob Alex
April 30, 2016

Physics
A 50 Kg box rests on a horizontal surface. The coefficient of Static friction between the box and surface is 0.30. The coeffient of Kinetic friction is 0.20. What is the frictional force on the box if a 140 N horizontal push is applied to it. If a 175 N horizontal push is ...
April 30, 2016

Math
The rectangular backboard of a basketball court needs to be assembled. Its area is given as 18,900 cm2 and the width as 1.8 m. What is the backboard’s length in metres? m
April 30, 2016

Chemistry
A gas occupies a volume of 4.64 x 102 mL at 519.57 mm Hg pressure. What will be its volume, at constant temperature, if the pressure is changed to 764.71 mm Hg?
April 27, 2016

Math
how to find out length of a rectangle area given 18900cm'2 width 1.8 what is length in metres
April 27, 2016

Math
Its area is given as 18,900 cm2 and the width as 1.8 m. What is the backboard’s length in metres? m
April 27, 2016

Math
Our parent function for log is log (x), so how does your function differ? 1) The leading negative sign. This reflects rhe function across the x-axis. 2) The (2 - x) inside the log function. Note that this is actually two transformations because 2 - x is equivalent to -x + 2. A...
April 27, 2016

Emergency Easy QUESTION
It depends on the colleges you're looking at and the high school you are attending. Colleges like to see rigor on your transcript so, if the college is very prestigious and your HS offered a lot of rigorous classes-- AP, gifted, honors, dual enrollment, etc.-- that might ...
April 27, 2016

English Grammar
Yes, that seems right to me. "I was referred... job," is a simple subject-verb-noun construction, "by... supervisor" is an adjective prep phrase describing "job opening," "John Smith" is the essential appositive, and the rest is ...
April 27, 2016

science
April 27, 2016

L.A.
Yes I meant L.A. I have no idea why I put Math. But thank you so much you helped me a lot!
April 27, 2016

Math
When Scrooge tells Marley that Marley was always “a good man of business,” in Act 1, Scene 3 of A Christmas Carol: Scrooge and Marley, Marley responds, “BUSINESS!!! Mankind was my business. The common welfare was my business; charity, mercy, forbearance, ...
April 27, 2016

Math
In order, these equations are: 1) .25x + 40 2) .40x + 25 Where the charge per minute is the slope, the flat rate the y-intercept. We want to know for what number of minutes these two plans cost the same, so set equations (1) and (2) equal to each other and solve for x.
April 26, 2016

algebra
Yes. A polynomial can have, at most, a number of zeroes equal to it's degree. A third degree polynomial can therefore have three zeroes, however, Ray is arguing that the polynomial has four INTERCEPTS. While the terms "zeroes" and "intercepts" are often...
April 26, 2016

Linear Algebra
Let T : Rn-->Rn be a linear transformation, whose standard matrix is invertible. Show that if B = {v1, . . . , vn} is a basis for Rn, then {T(v1), . . . ,T(vn)} is also a basis for Rn.
April 26, 2016

English
Because that's an arrogant, Anglo-centric point of view?
April 25, 2016

Calculus
This is actually a related rates question, so you want rates of change: so the rate of change of volume, the rate of change of surface area. This is represented as the derivative, but before you go finding the first derivative, think on how you should use the change of radius ...
April 25, 2016

Calculus
X and Y move perpedicular to each other, forming a right triangle. As such, the distance between the cars is sqrt(X^2 + Y^2), where X = +50 km/hr, Y = +60 km/hr. (These are functions.) We want the RATE at which these cars are seperating, so take the first derivative of the ...
April 25, 2016

PreCal
This set is numbers strictly greater than 2. Because this relation is strict (> instead of >=), the left interval is a parens. There is no upper bound, so the right interval is infinity. (2, +INF)
April 25, 2016

PreCal
That the price "dropped steadily" implies a linear relationship, which would simply be change in price over change in time. (140 - 90) / 5 = -\$10 / week.
April 25, 2016

Math
Follow order of operations. In the first parens, 33 + 19 = 52. The second parens is 51. Our expression is now 52 * 2 * 51. Multiplication is associative, so it doesn't matter which order we do this in. My calculator gives me 5304.
April 25, 2016

Algebra
I'm getting D.
April 25, 2016

cs 2
Which part of this assignment are you having trouble with? The logic? Or File I/O?
April 24, 2016

statistics
The problem wants the test statistic for a one-proportion z-test, which we know because we're only given data for 1 test and that "492 / 806" implies a proportion. The sample statistic for this test is given by sqrt(pq / n). p = 492/806 (probability of success) q...
April 24, 2016

statistics
So the population distribution-- the distribution of ALL M&Ms-- is given in the problem: N(0.8565, 0.0518). However, we want to know what the mean weight will be if, instead of pulling from ALL M&Ms, we "randomly select 465 M&M plain candies." This is our sample. ...
April 24, 2016

statistics
You are given a normal distribution of a population. You want to know things about a sample distribution, so you should start with constructing a normal distribution for your sample of 465 M&Ms. The mean of this sample remains the same. The standard deviation is the population...
April 24, 2016

statistics
The normal distribution is N(25, 10). P(X > 20) = .691 So approximately 69.1% passed the exam. 69.1% of 100 students is 69 students.
April 24, 2016

All statements are true. A rectangle simply requires that a four-edged figure has 4 right angles and two sets of parallel lines. A square is a special case-- that all four sides are the same length, but it's still a rectangle. The rest of your answers are correct. :-) It ...
April 22, 2016

math
What's the question?
April 22, 2016

physics
Er, what's the question?
April 21, 2016

math
y = -x + 8. (7, 1) corresponds to (x, y), so just plug in the values into the equations and see which one works. For the above equation, 1 = -(7) + 8 1 = 1 This is true, so this is indeed the correct equation.
April 21, 2016

math
Yes, quadrant IV is correct. :-)
April 21, 2016

Sampling Distributions
A - The sample standard deviation is the population standard deviation over the square root of the sample size, 30 / sqrt(36). The mean of an approximately normal sample distribution is the same as the population mean, so the sample distribution is N(360, 5). B - If you want ...
April 21, 2016

stat
We construct a binomial distribution. The probability of "success" (a substandard rod) is .05. We have 300 trials. B(.05, 300) P(X < 20) = .881
April 21, 2016

Physics
First convert your angular speed from rpm to rad/s. You can then convert your angular speed to tangential speed with v = omega * r. (Be sure to convert that diameter into SI units!) Newton's second law gives us F = ma, where this is centripetal acceleration, so F = (mv^2)/...
April 21, 2016

math
Sure, sounds good to me. :-)
April 21, 2016

math
I don't understand the question?
April 21, 2016

Bio
Because unique identifiers mean that, given a name, someone could find out about the organism. If we had two things with the scientific name "cat," that would be a problem-- there are tons of cats. But since no two species of cats have the same two names, given a ...
April 21, 2016

Bio
Ah, but each scientific name is unique. Chip brand names may be ridiculous-- Lay's, Doritos, Cheetos, etc.-- but they're unique so they still serve as good identifiers. (Can you tell I'm sitting next to a vending machine?) (Fun fact, ursus is also Latin-- most ...
April 21, 2016

Bio
D. All scientific names identify an organism's genus and species. Usually this name is Latinate (interesting-ish story involving Linnaeus), though it doesn't have to be.
April 21, 2016

Geometry
That's not a math error, that's a conversion error. Answers are in yards, lengths are given in feet. Cheap trick-- I just noticed it myself.
April 21, 2016

Geometry
Are you told that this is a right triangle? If you aren't, you'll have to law of cosines for the length of the third side. You could then Heron's for the area.
April 21, 2016

Statistics
I would say A, though that's because I was taught an 8-part procedure for hypothesis testing, and B - D are their own separate steps. It does make sense that you'd define your hypotheses in the hypothesis step, though, and you really shouldn't be calculating the ...
April 21, 2016

Educational Technology
April 20, 2016

Language arts
Without the passage, it's difficult to discern anything about questions 1-3. 4, however, should be D. The way the sentence is set up is to imply a contradiction, something like "Geese usually fly in a V formation but they aren't today." Unpredictable ...
April 20, 2016

Math
Here, let's define "success" to be that the plant doesn't grow. This would be 1 - .6 = .4. We construct a binomial distributions with 6 trials (6 seeds planted). We want 4 events. B(6, .4) P(X = 4) = .138
April 20, 2016

HELP PHYSICS PLS :)
This is a perfectly inelastic collision, so we know that energy is conserved. (Good job identifying the problem!) Assuming you choose your "0" PE point to be the bullet's initial height: E(i) = E(f) .5m(bullet)v(bullet)^2 = m(tot)gh(system), where h is the height...
April 20, 2016

Math PLZZZ HELP!!!
I'd go with the second and third choices. That the scatter plot has a positive trend tells you that you have a line of best fit with a positive slope. This satisfies both the second and third statements. The first answer assumes that all points on the graph fall exactly on...
April 20, 2016

Math
Multiply both sides of the inequality by 2. x <= -30, which is D.
April 20, 2016

Math
Are you sure that's all the data and that you typed that data in correctly? I haven't thrown this into my calculator, but just by observation, the range would be 27 - -52 = 79? None of those choices are correct if that's your complete data... (If you have to pick, ...
April 20, 2016

Physics
Let's start by converting everything to SI units. 15 m/hr/s = 6.71 m/s/s 65 m/hr = 29.1 m/s We have constant acceleration, so we can use our constant acceleration kinematic formulas. Here we initial velocity, final velocity, acceleration, and want time so we use v(f) = v(i...
April 20, 2016

Statistics
The probability of our event occurring is .8. We construct a binomial distribution, with 4 trials, of which we want 3 to occur. B(4, .8) P(3) = .4096
April 19, 2016

Math
Multiply both sides by 3729, yielding 3729tan(7)
April 19, 2016

Math
Actually, wait. You should be using tan, since you're given the adjacent side. (The lesson here: always draw a picture.) 120tan(36).
April 19, 2016

Math
The transit here is extraneous information-- it's simply a device used to measure angles (I assume). We know that the base of the right triangle is 120 feet. (Notice that the transit of 8ft is nonsensical in this problem doesn't make sense because we're solving for...
April 19, 2016

Math
Perimeter is the sum of all sides. For a rectangle, P = 120 = 2L + 2W. You are given that L = 3n W = n, so you can now do a substitution into the perimeter equation: 120 = 2(3n) + 2(n). Simplifying this, we get 120 = 8n, so n = 15. Revisiting our length and width equations, L...
April 19, 2016

Math
1/15.5 = 2/31
April 18, 2016

computer science
What specific part are you having trouble with? The packages? File I/O? What language?
April 18, 2016

calculus
Between y = 2x2 + 9x − 4 and y = −x2 + 6x + 2 for x in [−2, 2]
April 18, 2016

Language Arts
You are correct. :-) A conjunction joins two parts of a sentence together. A better example to describe this would be "Alice bought a calculator, and Ben bought a mouse." The conjunction "and" divides the sentence into two thoughts-- "Alice bought a ...
April 18, 2016

math
Set up a proportion: If Bill can type 10 pages in 24 minutes and we want to know how many pages he can do in 5.5 hours (330 minutes), a possible proportion is: 24/10 = 330/x Cross-multiplying we get 24x = 3300, so x = 3300/24 = 138 pages.
April 17, 2016

Algebra
The easiest way to justify this is to visualize the graph. We know from the first the signs of this equation that this quadratic opens upwards and know that it is shifted to be above the x-axis, so the quadratic never crosses the x-axis and therefore has no roots. You could ...
April 17, 2016

Net daily change is revenue - expenditures, 12500 - 15000 = -2500. The overall change in the treasury's funds is 1.1Mil - 1Mil = 100K. To find out how many days, we divide the overall change by the net daily change in revenue: 100K / 2500 = 40 days.
April 15, 2016

Algebra 2
If it's multiple choice, plug and chug those points. Otherwise, you have two options: 1) Quadratic Regression 2) Conics I opt for quadratic regression given that I've not done conics in three years, lol f(x) = -x^2 + 5x -4
April 15, 2016

Reverse math confused
Her preliminary cost (prior to tax and tip) is regular price (p) - 2. Tax and tip is 20% of this preliminary cost, so total cost is 9 = 1.2(p - 2). p = \$9.50. (Nice coupon, there...)
April 15, 2016

Math
We know that after cutting 1/3 of the coil and 8m of the coil, 1/2 of the coil remains. This can be written as 1/3 + x = 1/2, where x will be 1/6. We know that this 1/6 of the coil is 8m, so the total length of the coil is 8 * 6 = 48m because one coil = 6 subcoils each of 8m.
April 14, 2016

physics
Where is Q located? I'll explain how to do this, since I don't know enough about this problem. Solve for the the bob's velocity right before it hits ball Q using energy equations: U(bob) = KE(bob) + U(Q). From here you can use your elastic equations to solve for ...
April 14, 2016

math
The volume of the tank is 3885 cubic centimeters. Volume is equivalent to length * width * height, in which you are provided both length and width. Your equation becomes 3885 = 18.5 * 15 * height Solving this, we get height = 14 cm.
April 14, 2016

A quadratic equation's shape is a parabola. So anything with a curved trajectory would fit: throwing a ball / javelin / football / anything, shooting an arrow... Here's a fun picture: prntscr . com / arm214
April 13, 2016

test corrections for problems 6,11,12 and 23please
We want f(x) - g(x) and are given both equations. All you have to do is substitute: 9x^3=2x^2-5x+5 - (5x^3-7x+4) Be sure to distribute that negative sign! (I'd give you an answer but I'm not sure what that equals sign is supposed to be?)
April 13, 2016

test corrections for problems 6,11,12 and 23please
The sphere question is very similar to the cylinder question. Stick the provided value r into the provided surface area equation. SA = 4pi(2x+5)^2 Here you distribute / foil (2x+5) out when expanding, yielding 4pi(4x^2 + 20x + 25). Again, you should multiply each term by 4pi ...
April 13, 2016

test corrections for problems 6,11,12 and 23please
Oops. Add an x^2 to my previous answer. I wasn't sure why we had random x's in the problem, so I just dropped them. You're given the radius and the height of the cylinder. Simply stick in the given values into the provided formula and solve, yielding pi(80x^4 + 64x...
April 13, 2016

test corrections for problems 6,11,12 and 23please
A picture is helpful. Start by drawing the 8 by 12 lot. The field must fit in this lot and is 3 by 6. The area that is not the field is the remaining area. This is a simple area calculation. Total area of the lot is 8 * 12 minus the area of the field, 3 * 6. The remaining area...
April 13, 2016

Math
Yes, 76%.
April 13, 2016

Integers
From the problem statement, we know that some 6 integers must sum to 171. To get an idea of what these numbers are, start by dividing 171 by 6. This yields 28.5, which is what the average of our numbers are. Here we can construct numbers close to this interval-- the problem ...
April 12, 2016

Maxima and minima Application
This is a parabola, so it can either open upwards and have a min but not a max or open downwards and have a max but not a min. From the sign of the leading term (+1), we know this opens up. The minimum position of this parabola would be the point of symmetry. To find this, we ...
April 12, 2016

math
From the prompt, we know that: a) L = W + 2 b) Perimeter = 28 = 2L + 2W Where I call breadth W The easiest way to solve this system is by substitution. Plug in (a)'s value of L into b, yielding 28 = 2(W+2) + 2W. From here, isolate and solve for W. You should get W = 6cm. ...
April 12, 2016

Math
1) Picture the equation. It must decrease at an unknown rate, then flatten out as it nears 60K (asymptote). This would be in the family of functions of 1/x because 1/x is the most common function to have asymptotes, which Google seems to call power / reciprocal / rational / ...
April 12, 2016

Math
175 / 625 = 28% (What kind of party lasts 6 hours?)
April 12, 2016

Math
Only a dilation would change the shape's dimensions-- any type of shift would simply relocate the shape. We must only prove that dilation do not change the concurrency. Dilations, by definition scale on object-- if you dilate it by 2, the second image will be exactly twice...
April 12, 2016

Science
A - True. B - False. ATP -> ADP releases energy. C - False. ADP -> ATP represents storing energy. (Also you can't "break down" ADP into ATP.) D - False. Glucose and ADP / ATP can both store energy.
April 12, 2016

physics
A) This is a conservation of energy problem, so E(i) = E(f). I'll pick our point of origin to be the spring's equilibrium height-- this makes the gravitational potential energy of the ball easy to calculate. We now identify what types of energy are present at the ...
April 12, 2016

Math
Start by calculating the area of the desk. Area of a rectangle is base x height, 5.5 * 3.5 = 19.25 ft^2. Now calculate the area of the tile: .5 * .5 = .25 ft^2. To figure out how many tiles can fit, divide the area of the desk by the area of one tile: 19.25 / .25 = 77 tiles.
April 12, 2016

math polynomials
I'm assuming you're solving for x? Set each term in parentheses equal to 0, yielding: ~ 3x + 4 = 0 ~ x - 2 = 0 Now isolate x and solve. For the first equation, this would be subtracting 4 from both sides, then dividing by three. x = -4/3, 2
April 12, 2016

PHYSICS Momentum!! Collision HELP
Your assumption is correct. If you simply choose initial to be "before the collision," a) P(iA) = 0.202 * 2 P(iB) = 0 b) KE(iA) = .5 * .202 * (2)^2 KE(iB) = 0
April 12, 2016

Linear Algebra
p1, p2, p3 are elements of P_2 p1(x)= 1+x-2*x^2 p2(x)= 2+3x-x^2 p3(x)= 3+5x-x^2 Is S = {p1, p2, p3} linearly independent?
April 10, 2016

math
Take natural log of both sides. therefore ln(15)=ln(2^x) move x to the front ln(15)=x*ln(2) move ln(2) to the other side therfore x=ln(15)/ln(2) write all this down on paper to see it properly.
April 10, 2016

Algebra
A basketball player makes 53 points on 24 shots. How many 3 pointers and 2 pointers did he shoot. Show your work. I know that the answer is 5 for the 3 pointers and 19 2 pointers but I don't know how to show it.
April 7, 2016

Science
PLEASE HELP 1. Katie is bowling. She starts with the ball in her right hand and her arm as far back as it will go. She swings the ball forward, applying a force of 78 Newtons the whole time. When her hand has traveled through a path of 0.9 meters, she releases the ball, and it...
April 4, 2016

Chemistry
What is the pH of the solution when 50.00 mL of 0.250 M HNO3, nitric acid, has been treated with 25.00 mL of 0.400 M NaOH? Below is the work I performed, however, my professor deemed the [H3O] as incorrect. Where did I go wrong? [NaOH] = .025 L x 0.400 M = .010 mol [HNO3] = ....
March 30, 2016

Derulo
13 more than the product of M & 5
March 29, 2016

The 5th Wave
Yes yes and yes
March 29, 2016

math
Marcela 27 donuts from Dunkin Donuts. She ate one ninth of the donuts. She took the remaining donuts and shared them equally amongst 12 classmates. How many donuts did each friend receive?
March 21, 2016

math
Marcela 527 donuts from Dunkin Donuts. She ate one ninth of the donuts. She took the remaining donuts and shared them equally amongst 12 classmates. How many donuts did each friend receive?
March 21, 2016

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