# Posts by ray

Total # Posts: 636

**Math**

If two cars started out at the same spot and traveled in opposite directions for 90 minutes at 60miles per hour -far apart in total miles would they be at the end of the 90 minutes?

**Math (Evaluating integrals)**

I am trying to prepare for my finals and I'm approached with this question where I'm not entirely clear what the answer should be: Given the function h(t) graphed below, define A(x) = ?[-0.5,x] h(t) dt . (Graph is in the link) goo.gl/photos/YZuHtnUK2UPwpaq1A Evaluate A...

**Math (Sorta dumb question)**

I'm given the equation S = L(1 - e^(-kt)) I am asked to write S as a function of t when L = 100, S = 25 when t = 2 So would my final answer just have S and t as variables? Or have S, t and L as variables? Ended up with S = 100(1 - e^((ln(3/4)/2)*t) Or is the actual answer ...

**Banned for cheating!**

It seems like this test cheating issue is more of a recent problem? I've been on this site for over 2 years but only now I've started noticing that there's multiple bans for asking test answers each day :/

**Math (Calc) (Differential Equations)**

Ahh I see now. Thanks for your help!

**Math (Calc) (Differential Equations)**

The rate of change in the number of miles s of road cleared per hour by a snowplow is inversely proportional to the depth h of snow. That is, ds/dh = k/h Find s as a function of h given that s = 25 miles when h = 3 inches and s = 10 miles when h = 9 inches (2 <= h <= 15...

**Math (Calc) (Differential Equation Solution)**

Some of the curves corresponding to different values of C in the general solution of the differential equation are shown in the graph. Find the particular solution that passes through the point (0, 2). y(x^2+y) = C 2xy + (x^2+2y)y' = 0 How would I start this problem to ...

**Math (Calculus II) (Volume Revolution Setup)**

Thanks for the help Steve! Greatly appreciated!

**Math (Calculus II) (Volume Revolution Setup)**

Take the area enclosed by the curves y = sqrt(x), y = 1, and x = 4. Rotate it around the line x = 5. Find the volume. While I understand the general problem would call for the shell method ?[a,b] 2*pi*r*h dx With r = 5 - x and h = sqrt(x) - 1 But, what happens say if the ...

**Math (Double checking trig identity)**

So tan^2? is where I messed up, thanks Steve!

**Math (Double checking trig identity)**

Since sec^2? - 1 = tan^2? I know this is trivial, but I want to make sure I'm doing this right before I apply it to the integral I'm trying to solve... If I have some constant a, (a^2sec?)^2 - (a^2)^2 If I wanted to change this to tan would it be: a^4tan^4?? Any help ...

**Math (Calculus II) (Partial Fraction Decomposition**

I'm having trouble trying to solve for the partial fraction decomposition in order to find the integral. ? x / (x^4 - a^4) dx I'm assuming a is some constant in this case. So I factored the denominator to this: (x^4 - a^4) = (x^2 + a^2)(x + a)(x - a) Which turns each ...

**Math (Calculus II) (Weird Work Problem Setup Help)**

Correction, I typed the integral wrong! Forgot to include the distance: dF = 53.1(3)(2 - (y/3)) dy dw = dF * Distance W = ? 53.1(3)(2 - (y/3)) (y + 3) dy W = 3106.35 ft-lb

**Math (Calculus II) (Weird Work Problem Setup Help)**

I am trying to understand my teacher's example of a Work problem. Cut to the chase here's a picture of the problem: goo.gl/photos/AqZ6ENmHLg6heixD7 While I understand how to integrate fairly well, I'm still confused on how exactly my teacher set up the work problem...

**Math (Integrals) (Volume of Revolution Setup)**

I am supposed to find the area of the region given two boundaries and two functions revolving about the x axis. x = 0 x = pi/2 y = cos(x/2) y = sin(x/2) Graphing those two functions made me select to use the washer method. Therefore, I set my definite integral to this: pi?[0,...

**Math (integrals) (Trig Subsititution)**

Woah, I don't think there's a need for i in this problem. This is how I end up doing the problem: ?(sqrt(5)sec^2(?)) / (5tan^2(?) + 5)^(3/2) d? ?(sqrt(5)sec^2(?)) / (5sqrt(5)sec^3(?)) d? Simplifying.. ?(sec^2(?)/ (5sec^3(?)) d? (1/5) ? (sec^2(?) / (sec^3(?)) d? (1/5...

**Math (integrals) (Trig Subsititution)**

Find ?1/((x^2+5)^(3/2)) dx I figured this would be a trig substitution problem, so I set x = sqrt(5)tan? and dx = sqrt(5)sec^2(?) d? This would lead to: ?(sqrt(5)sec^2(?)) / (5tan^2(?) + 5)^(3/2) d? But I'm kinda lost on what to do next. I'm used to breaking up the ...

**Math (Integrals) (Using given method)**

Thanks! So I was on the right track, but messed up near the ending.

**Math (Integrals) (Using given method)**

I would like to solve the ?sin^2(pix) dx Using the given substitution identity: sin^2(x) = (1/2)(1-cos2x) This is what I did so far: ?sin^2(pix) let u = pix du = pi dx (1/pi)?sin^2(u)du Applying the identity is where I'm lost on how to continue further.. (1/pi)?(1/2)(1-...

**Math (Integrals) (Using given method)**

?sin(x)cos(x) dx Using the identity sin(2x) = 2 sin(x) cos(x)?

**Math (integrals) (Substitution)**

I am given an integral to solve with given substitution values. I got an answer, but I'm not quite sure if it's correct as an online integral calculator gave a different answer. ? x sqrt(4-x) dx Given that u = 4-x . In this case, x = 4 - u du = -dx Now.. =- ? (4-u)sqrt...

**Math (Calculus) (Work)**

1.73 ft-lb*****

**Math (Calculus) (Work)**

Woops, I didn't convert 1/2 inch to feet. the W equation should be [1/3,9/24], leading to the answer to be around 1/73 ft-lb

**Math (Calculus) (Work)**

Six and one-half foot-pounds of work is required to compress a spring 4 inches from its natural length. Find the work required to compress the spring an additional one-half inch. (Round your answer to two decimal places.) This is what I did so far: 4 in = 1/3 ft 6.5 = ?[0,1/3...

**Math (Calculus II) (Volume Revolution Setup)**

Thanks! Would we want to use shells of thickness dx and symmetry for (c) as well?

**Math (Calculus II) (Volume Revolution Setup)**

Consider the graph of y^2 = x(4-x)^2 (see link). Find the volumes of the solids that are generated when the loop of this graph is revolved about (a) the x-axis, (b) the y-axis, and (c) the line x = 4. goo.gl/photos/v5qJLDztqsZpHR9d7 I'm just having trouble trying to set up...

**P.E**

I'm not Ms. Sue, but I would say B would affect your health in a negative way. When a person is angry, if the person chooses to simply ignore their triggers, it would only makes matters worse over time.

**Math (Integrals)**

? (2x-1)^2 dx could have two answers: a) ((2x-1)^3)/6 + C b) 4/3x^3 - 2x^2 + x + C Now the question is, how are the two answers related? I attempted to answer the question by: "The two answers are related because when finding the derivative of those two different answers...

**Math (Integrals) (Basic Integration)**

Yeah I see it, I just tend to overthink way too much than I should so I end up asking obvious questions. My apologies. Thanks so much for the help!

**Math (Integrals) (Basic Integration)**

So, why is it that we can't use the easy trick method for the first one? Is it because of the "1" on the numerator that isn't a variable?

**Math (Integrals) (Basic Integration)**

I am given two integrals a and b a) ? 1/(1 + x^4) dx b) ? x/(1 + x^4) dx The main difference between the two integrals appears to be the "1" and "x" on the numerators. While they both resembles closely to the basic integration of arctan: ? du/(a^2 + u^2) = ...

**Math (Integrals)**

Find the indefinite integral in two ways. ?(2x-1)^2 dx The first way I used was using the power rule and chain rule with substitution. Let u = 2x - 1 du = 2 dx (1/2)? u^2 du (Applying power rule) (1/2) * (u^3/3) + C =(2x-1)^3/6 + C What would be another way of finding the ...

**Chemistry**

how much energy is released during the reaction of 2.5l diboron hexahydride with 5.65l chlorine gas?

**Math (Integrals)**

The area A between the graph of the function: g(t) = 4 - (4/t^2) and the t-axis over the interval [1, x] is: A(x) = ?[1, x] (4 - (4/t^2)) dt a) Find the horizontal asymptote of the graph g. I believe the horizontal asymptote of graph g is g(t) = 4. b) Integrate to find A as a ...

**Math (Definite Integrals)**

Should we assume r = 1?

**Math (Definite Integrals)**

Sketch the region given by the definite integral. Use geometric shapes and formulas to evaluate the integral (a > 0, r > 0). r ? sqrt(r^2 - x^2) dx -r While I recognize that this looks similar to a circle function, I'm not sure how to graph and evaluate this definite...

**Math (Calculus) Integrals**

Can't believe I forgot about that simple rule, thanks for the recall!

**Math (Calculus) Integrals**

Evaluate the integral using the following values. 8 ? x^3 dx = 1020 2 8 ? x dx = 30 2 8 ? dx = 6 2 2 ? x^3 dx = ? 2

**Math (Calculus II) (Graph approximation)**

Any ideas? Really need help on this one

**Math (Calculus II) (Graph approximation)**

Here is the link to the graph of f' in question: bit.ly/2oml70V I have a hard time trying to answer these kinds of questions when we're only given a graph of f'. a) Approximate the slope of f at x = 4. Explain. I believe the slope of f in this case would be a ...

**biology**

HELP PLEASE!!!! How does the outcome of a chemical reaction that absorbs energy differ from one that releases energy?

**Math (Stats)**

Well we only use the regression line for predictions if the regression is a reasonable fit for the data, the correlation coefficient is significant, and the data for the predicted values do not go beyond the scope of the data used to estimate the regression. B

**Math (Stats)**

In order to predict y-values using the equation of a regression line, what must be true about the correlation coefficient of the variables? A. The correlation between variables must be an x-value of a point on the graph. B. The correlation between variables must be significant...

**Alebra 2**

At what point does the terminal side of the angle (5\pi )/(6) in standard position intersect the unit circle?

**math **

Elijah made an array of Skittles with 3 rows and 4 columns. Josh made an array of peanuts with 4 rows and 2 columns. Jake made an array of M&M's with 2 rows and 5 columns. What is the total of the candy? -Is it 30?

**Math**

The population of bacteria in a petri dish doubles every 12 h. The population of the bacteria is initially 500 organisms. How long will it take for the population of the bacteria to reach 800? Round your answer to the nearest tenth of an hour.

**Math-Geometry**

I am having a difficulty with solving proofs, such as triangle proofs for my homework, is there any tips and tricks to be able to solve them?

**Math (Octants identifying) *emergency***

How would I identify a set of coordinates (x, y, z) to be in which octant in a 3d space? Is it just based on the x-value? Depending on the x-value (1-8) used?

**random**

this website is so helpful but i am confused on some things 1) the people who answer questions is this their job or are they volunteering to for free and what do they gain out of this 2)do the tutors who answer questions sit at home and answer or at some work place 3) how ...

**chemistry**

i thought this was physics

**riddle**

The answer is SEX...its old to those whose who have tried it eg married couples but its new to virgins

**Math (misleading graphs) (Statistics)**

Thanks so much!

**Math (misleading graphs) (Statistics)**

When constructing a graph showing the population of two? countries, an illustrator draws two different people with heights proportional to the populations. Identify a way in which the graph might be misleading. What is the general name for such graphs that use drawings of ...

**Math (Stats)**

It's C because class limits and class boundaries cannot be the same!

**Math (Stats)**

What is the difference between class limits and class boundaries? A) Class limits are the numbers that separate classes without forming gaps between them. Class boundaries are the least and greatest numbers that can belong to the class. For integer data, the corresponding ...

**Computers (RAM) **

Just giving this a shot, Which of the following statements about RAM are TRUE? Select all that apply. a) Any part of RAM can be accessed at any time. b) RAM is an area of a computer that holds programs and data that are waiting to be processed, to be stored on permanent basis...

**Chemistry (percent abundance) *emergency***

If the average atomic mass of Br is 79.90 amu, what is the percent abundance of each of its isotopes? How would we figure out the isotopes first before we calculate the percent abundance??

**Math (calculus) (mean values)**

So basically round up this time, wow!

**Math (calculus) (mean values)**

A company introduces a new product for which the number of units sold Ss given by the equation below, where t is the time in months. s(t) = 155(7-(9/(2+t))) a) Find he average rate of change of s(t) during the first year. I got the answer to be 1395/28 b) During what month of ...

**Math (optimization) really confused**

Right! Which apparently that isn't the right answer! I did pretty much exactly what @Damon and @Steve but my teacher marked it as wrong. What gives?????

**Math (optimization) really confused**

A rectangular fenced enclosure of area 225 square feet is divided half into 2 smaller rectangles. What is the minimum total material needed to build such an enclosure?

**Math (related rates) help?**

Hi there, wouldn't we need to use right triangle trig for this problem since it's asking for the rate of the angle? theta? Not completely sure on how to relate that exactly.

**Math (related rates) help?**

A 13ft ladder slides down a wall at 2ft/sec when it is 12 ft above the ground. Find the rate at which the angle it makes with the ground changes at this moment?

**Chemistry (identifying equations)**

What type of reactions are these? Acid-base? Oxidation/Reduction? Precipitation? 1) Zn (s) + 2 HCl (aq) -> ZnCl2 (aq) + H2 (g) 2) Fe (s) + CuSO4 (aq) -> FeSO4 (aq) + Cu (s) 3) Fe (s) + Cu(NO)2 (aq) -> Fe(NO3)2 (aq) + Cu(s)

**Chemistry (equlibrium direction) urgent**

Consider the endothermic reaction 2 NO(g) <-> N2(g) + O2(g) -If I decrease the volume of the vessel and increasing the total pressure in the vessel, what direction will the equilibrium will shift? (left/right) (I know that decreasing the volume would shift to produce ...

**Chemistry (molarity) *emergency***

Hi there, maybe dumb question but how would I find the initial concentration of Fe^3+?? In lab, we mixed these reactants into one test tube: -0.50mL of 0.0025M Fe(NO3)3 -0.50mL of 0.0025M KSCN -2.50mL of 0.10M HNO3 The net ionic equation for the experiment is: Fe^3+(aq) + SCN...

**Math**

On level ground, a 60-foot-tall vertical building casts a 10-foot shadow. at the same time, another vertical building casts a 25-foot shadow. how many feet tall is the second building?

**physics**

An object of mass 5 kg weighs 30 N on planet Z. The acceleration due to gravity on planet z is? a) 30 m/s^2 b) 10 m/s^2 c) 6 m/s^2 d) 0.17 m/s^2 e) 150 N

**physics**

It takes 5 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?

**Chemistry (Molarity) Help**

So there's this prelab assignment we're supposed to complete where we would fill out this table with [FeSCN^2+] in each of the test tubes. I'm not completely sure on how to do this? For example, on the first tube calculate the molarity of [FeSCN^2+] with the data ...

**Chemistry (Dilution) Help please?**

Calculate how to prepare 100.0mL of a 1.25x10^-4 M aqueous solution of Fe(NO3)3(aq) by dilution of stock of 0.0025M Fe(NO3)3(aq) in a 100.0mL volumetric flask? I tried using the m1v1=m2v2 equation but it doesn't look like that equation would work for this problem??

**Math (Calculus) (Related Rates)**

A boat pulls away from a dock at 2 m/s, but the operator has neglected to remove the tow rope used to pull the boat up to the dock. This rope runs thru a pulley which is attached to the dock at a point 1 m higher than the point at which the rope is attached to the boat. A) How...

**Math (Calculus) (Related Rates)**

A boat pulls away from a dock at 2 m/s, but the operator has neglected to remove the tow rope used to pull the boat up to the dock. This rope runs thru a pulley which is attached to the dock at a point 1 m higher than the point at which the rope is attached to the boat. A) How...

**Math (calculus) (optimization)**

Found the answer, it was a calculator error but r is actually~6.2035 leading h~24.8141

**Math (calculus) (optimization)**

A solid is formed by adjoining two hemispheres to the ends of a right circular cylinder must have a volume of 4000 cubic feet. The hemispherical ends cost twice as much per square foot of surface area as the sides. Find the dimensions that will minimize cost. I got as far as ...

**Math (calculus) (mean values)**

Got the same answer, 3.29 which is around march, but that answer was not correct according to the website

**Math (calculus) (mean values)**

A company introduces a new product for which the number of units sold S is given by the equation below, where t is the time in months. s(t)=155(7-9/(2+t)) a) Find the average rate of change of s(t) during the first year. Which my answer was 1395/28 b) During what month of the ...

**Algebar**

81x^(6)-25y^(10) Factor

**Math (Calculus) (mean value theorem emergency)**

b) Using the mean value theorem gave me f'(c)=1 and solving for c gave me 1 as well. c) Tangent line y=x-13 I checked with a graphing calculator and my answers look right

**Math (Calculus) (mean value theorem emergency)**

Consider the graph of the function f(x)=x^2-x-12 a) Find the equation of the secant line joining the points (-2,-6) and (4,0). I got the equation of the secant line to be y=x-4 b) Use the Mean Value Theorem to determine a point c in the interval (-2,4) such that the tangent ...

**Math (Differentials)**

Oh! Minor mistake, thanks for the help!

**Math (Differentials)**

Use differentials to approximate the value of the expression. cube root of 25 I set x=27 and dx=-2 and got ~3.0741, what did I do wrong?

**Math (equation of tangent line)**

I had that on the back of my head when I was doing this but thought that wouldn't be possible, thanks so much!

**Math (equation of tangent line)**

Any ideas anyone? I need to have this turned in by tomorrow, any help is greatly appreciated

**Math (equation of tangent line)**

Maybe my derivative isn't correct in the first place? I used the quadratic formula to solve for x and got x being equal to -1 but when I plug that into the equation I get 0/0, which certainly means I'm doing something wrong. Any ideas?

**Math (equation of tangent line)**

Consider the implicit equation 2xy-1=(x+y+1)^2 a) Compute and solve for the derivative dy/dx as a function of x and y. b) Find the equation of the tangent line to the graph of the above when y=-1. For part a, I found the derivative being equal -(x+1)/(y+1) but how would I find...

**Math (Slope of inverse tangent line)**

a) 2 b) 1/2

**Math (Slope of inverse tangent line)**

Given the graph, goo.gl/photos/VTMjKvNsVvAQwe3X6 a) What is the slope of the tangent line to the graph of f^-1 at the point (-1/2,-1)? b) What is the slope of the tangent line to the graph of f^-1 at the point (1,2)?

**Science (Stoichiometry with Gasses) (Chemistry)**

If 1.00 kg of methane (CH4) is burned completely (in excess O2) and the CO2 produced is collected at 20°C and 1.00 atm, what volume (L) will this CO2 occupy??

**Chemistry (Mass/volume)**

What are factors that will contribute to achieving the lowest mass/volume ratio possible for an airbag? The "mass" includes the mass of the reactants, bag, and any additional materials you would use to make the airbag. The "volume" is of the inflated air bag.

**Math checking answers (Calculus Differentials)**

The radius of a spherical balloon is measured as 8 inches, with a possible error of 0.02inch. a) Use differentials to approximate the possible propagated error in computing the volume of the sphere. b) Use differentials to approximate the possible propagated error in computing...

**Chemistry (molarity) (sorta an emergency)**

It looks like it's the same answer, but how we got to it was different. With your equation, that's what I would take on for this lab, but my chemistry teacher warned us a million times to NOT do it that way, don't know why, but she wanted us to do it the way I ...

**Chemistry (molarity) (sorta an emergency)**

I'm doing a titration lab and writing a lab report where I'm sort of stuck on how exactly to find the concentration of HCl. These are the following info I have from the lab, Equation: HCl(aq)+NaOH(aq)-> H2O(l)+NaCl(aq) -Calculated molarity of NaOH solution is .103M...

**Math (Derivative)**

This leaves with dy/dt=12(-.75/8) dy/dt=-1.125 dy/dt=-9/8

**Math (Derivative)**

Finally figured out, simply plug the given x value into the original equation!

**Math (Derivative)**

Assume that x and y are both differentiable functions of t and the required values of dy/dt and dx/dt xy=6 a) Find dy/dt, given x=8 and dx/dt=12 b) Find dx/dt, given x=1 and dy/dt=-8 I started with a and got dy/dt=dx/dt(-y/x) Plugging with the given values leaves me with dy/dt...

**Chemistry (molarity)**

How would I find the moles of NaOH solution that was used to titrate? I have 20.01mL of HCl used and 15.95mL of NaOH solution was used to titrate.

**Chemistry (molarity)**

DrBob222 you're exactly right on 2! Sorry my teacher didn't really clarify exactly what was being asked but I took on the question like how #2 is stated, and therefore said that the molarity of the NaOH wouldn't be affected by the amount of water added prior to the...

**Chemistry (molarity)**

Yes I know the formula of molarity M=mol/L but the volume of water is not accounted for in this calculation specifically since the volume we're using is the volume of NaOH solution dispensed into the flask. Therefore, water shouldn't have an effect on the molarity of ...

**Chemistry (molarity)**

Btw, KHP is Potassium hydrogen phthalate C8H5KO4