Thursday
June 30, 2016

Posts by dave

Total # Posts: 758

Diffeq
d/dx (x)(e^xy)(cos2x). Product rule lets me take the derivative of f(x)g(x). But three functions?
February 11, 2011

Math
Please Help! (R=restaurant) If R1 is 480-8t-0.8t^2 and R2 is 254+0.78t, how would I write a function (R3)that represents the total sales for the the two restaurants?
February 9, 2011

PreCalculus
(R=restaurant) If R1 is 480-8t-0.8t^2 and R2 is 254+0.78t, how would I write a function (R3)that represents the total sales for the the two restaurants?
February 9, 2011

maths
if two sides must be parallel then the fourth side is also 3.5 cm add the sides = perimeter
February 6, 2011

English
I would shy away from first person unless specifically to write from that perspective.
February 6, 2011

maths
1km = 1000 m 100cm = 1 m convert to meters and divide
February 6, 2011

math
check out law of cosines
February 6, 2011

chemistry
Fish-liver oil is a good source of Vitamin A. When 0.1232 g of fish liver oil is dissolved in 500. mL of solvent, an absorbance of 0.724 is recorded. When 0.00167 g of Vitamin A is dissolved in 250. mL of solvent, an absorbance of 1.018 is recorded. Calculate the mass percent ...
February 6, 2011

Math
The additive inverse is the # which when added to a number equals zero. If you consider 12 on the clock to be '0", the -3 and 9 would both have 3 as an "AI"
February 6, 2011

Physics
Thanks, I couldn't find an equation that derives the max velocity of the pendulum in my textbook.
February 5, 2011

Physics
Find the speed of a pendulum bob at the bottom of its swing if its initial displacement is 5 degrees and its period is 2 s.
February 5, 2011

Physics
Thanks. I was confused by the way the question was worded and my answer was 2 times bigger than what the answer is supposed to be.
February 5, 2011

Physics
A child of mass 40.0 kg is swinging on a swing with ropes of length 4.0 m. How long does it take the child to swing from the maximum height on one side to the other?
February 5, 2011

Science
equal, opposite
February 5, 2011

Social Studies (geography)
do a search for maps of the world / lat /long
February 5, 2011

Math
replace n with inf. 1 + (-1^0/0) = 1 +(-1^0) = 1+1= 2
February 5, 2011

Math
The additive inverse is the # which when added to a number equals zero. interesting questions. If you consider 12 on the clock to be '0", the -3 would have 3 as an "AI". If you consider the number you are starting from to be "0" then = or - 12 ...
February 5, 2011

STATISTICS
The experiment was not 'double blind" because the same person who compared the test scores (the professor) was aware of the reason for the experiment. If the groups were aware of the reason for them playing the games (possible affect on test scores) this would be ...
February 5, 2011

algebra
for every increase of 1 in x, y decreeases by 3 this gives us 3x y=0=23 so, y=23-3x
February 5, 2011

chemistry
ahh, of course, thank you.
February 5, 2011

chemistry
Consider a red flame color produced by excited lithium with a wavelength of 671 nm. What is the mass equivalent of 1 mol of photons of this wavelength? I can get as far as Js of E Can't seem to find equation to turn Js into mols, or photons into mols, for Js into photons. ...
February 5, 2011

Algebra
1 * 10^-3 = .001 1 * 10^-4 = .0001 1 * 10^-5 = .00001 Get the Idea?
February 5, 2011

science
what would happen if you mixed isopropanol with copper and dranked it
February 5, 2011

Calculus
y-(-4)= 5/2(x-3)-b this should be slope intercept FORM of what you wrote.
February 5, 2011

chemistry
what would happen if you mixed isopropanol with copper
February 5, 2011

Math 156
an infinity of shapes can have two right angles provided they have more than three sides and the sum of the inside facing angles minus the sum of the outside facing angles equals 180 degrees.
February 5, 2011

chemistry
h*c/lambda would this be planck's constant times speed of light / wavelength?
February 5, 2011

chemistry
An electron in the n = 5 excited state of a hydrogen atom emits a photon of 1281 nm light. To what energy level does the electron move? Any ideas on an equation for this? Is it some kind of backward version of Rydburg Eq?
February 5, 2011

MATH
correct. can be written as just 9s^2 - 4d^2
February 5, 2011

MATH
let x be ttl $ spent (2.75 * days) y=110-x
February 5, 2011

Math
You have two problems here. 1. need D:f(x) = 2sqrtx 2. subsitute x=4 into derivative D: 2sqrtx : a) multiply power times coefficient; 1/2 * 2 = 1 b)power - 1 = 1/2 -1 = -1/2 c. f'(x) = x^-1/2 or 1/sqrtx substitute 4 for x and you should be there
February 5, 2011

math
yup
February 5, 2011

physics
blocks A and B weigh 10 lb and 40 lb, respectively. A and B extend over a fixed drum, one on reach side. Determine the acceleration of A and the tension in the cord if the fixed drum is smooth.
February 3, 2011

Math
If a cube has one edge of 2m, what is the surface area of this cube?
January 17, 2011

chemistry
The heat of vaporization of a substance is 2900 J/g at its boiling point of 313C. How much of this substance can be vaporized if 58700 J of energy are available?
January 17, 2011

Math
What is the sum of the measures of the interior angles of an 11-side polygon?
January 12, 2011

Geometry
If ∆ ABC ~ ∆ DEF, BC = 12 cm, EF = 10 cm, and AC = 18 cm, find DF.
January 11, 2011

business
Your manager has asked that you reach out to three senior leaders in the organization to build a better understanding of their needs so that your department can better align themselves with these executives’ and build partnerships for new work. Where will you look for ...
January 10, 2011

earth
What does the word anti mean? My answer- is opposed to something????? Please help me
December 6, 2010

chemistry
I ALSO NEED HELP
December 6, 2010

Physics - bungee jumping
The gravitational potential energy of the jumper is mgh, where m is 60kg and h is 22m - 1.8m or 20.2m. The PE of the bungee at full length is 1/2kx^2, where x is the difference between stretched and unstretched length, i.e. 20.2m - 12.2m or 8m. Setting these to equal: 1/2kx^2=...
December 4, 2010

Math/Statistics
The mean starting salary for graduates in the spring of 2004 was $36,280. Assume that the distribution of starting salaries follows the normal distribution with a standard deviation of $3,300. What percent of the graduates have starting salaries between $35,000 and $40,000? a...
November 29, 2010

Math
Solve the equation- e^x2+5x+6=1
November 25, 2010

statistics
1. Test the Nation on CBC:“Test the Nation” was the biggest survey ever conducted to see just how smart Canadians are. In this live two-hour special, 1.5 million Canadians participated in a real-time interactive IQ test. Viewers took the test in the comfort of their ...
November 22, 2010

Trigonometry
You observe a plane approaching overhead and assume that its speed is 700 miles per hour. The angle of elevation of the plane is 16° at one time and 58° one minute later. Approximate the altitude of the plane
November 22, 2010

Physics
You weigh 585N on Earth, what is your mass? What do you weigh on the moon id g is 1.60m/s2
November 18, 2010

st elizabeth technical
1. What would you think of a company's ethics if ti changed accounting methods every year? 2. What accounting principle would changing methods every year violate? 3. Who can be harmed when a company changes its accounting methods too often? How?
November 15, 2010

World History
farming
November 14, 2010

chemistry
(1)acid+base=.1M potassium dibasic phosphate: 7=12.67 + log(base/acid) (base/acid)=2.138x10^-6 subst. in (1) base+base/2.138x10^-6=.1 solving base=2.13x10^-7M Mass of base=2.13x10^-7 x (174.18g)=3.71x10^-5g Now I can find the mass of the acid as well by substituting for the ...
November 14, 2010

chemistry
I should have given more info. I figured that I would use the H-H equation and the total conc., but what I don't get is why do I need two pka's. I can get to the mass easily, but it seems that I could use either pka=7.21 or 12.67 with the base +acid =.1M.
November 14, 2010

chemistry
Calculate the mass of salts needed for constructing a buffer using potassium monobasic phosphate and potassium dibasic phosphate with the total concentration of 100 mM. The solution is to be prepared in DI water and the pKa value for potassium monobasic phosphate is 7.21 and ...
November 14, 2010

geometry
what are the possible coordinate of the midpoint of the given segment
November 8, 2010

algebra
factors
November 7, 2010

Algerbra
10,000(1-n/20)=6500 please show work
November 7, 2010

english
8. In Frost’s poem “Mending Wall,” the lines “I see him there, / Bringing a stone grasped firmly by the top / In each hand, like an old-stone savage armed” uses which poetic device?
November 7, 2010

math
log8 4(square root sign) 1/2
November 7, 2010

Math
you werent supposed to include the 1-
November 6, 2010

Math
Write the following logarithmic equation in exponential form? 1- log0.001 = -3
November 6, 2010

math
thank you
November 6, 2010

math
a baseball team buys 15 bats for $405. aluminum bats cost $25 and wooden bats cost $30. how many of each type did they buy? Please show work
November 6, 2010

6th grade
Your stupid...
November 3, 2010

Chem.
Acetic acid (CH3COOH) reacts with isopentyl alcohol (C5H12O) to form isopentyl acetate (C7H14O2), a fragrant substance with the odor of bananas. CH3COOH + C5H12O -> C7H14O2 + H2O If the yield for the reaction is 45%, how many grams of the product are formed when 3.58 g of ...
October 31, 2010

Chem
Acetic acid (CH3COOH) reacts with isopentyl alcohol (C5H12O) to form isopentyl acetate (C7H14O2), a fragrant substance with the odor of bananas. CH3COOH + C5H12O -> C7H14O2 + H2O If the yield for the reaction is 45%, how many grams of the product are formed when 3.58 g of ...
October 31, 2010

Chemistry
A 2.50 gram sample of bronze was dissolved in sulfuric acid. The copper in the sample reacted with sulfuric acid to form copper sulfate. Cu (s) +2 H2SO4 (aq) -> CuSO4 (aq) +2 H2O (l) The copper sulfate formed in this reaction was mixed with I to form copper iodide: CuSO4 (...
October 31, 2010

math
A tugboat can go 10 miles upstream in the same time as it can go 15 miles downstream. If the tugboat goes 12 miles per hour in still water, what is the speed of the current?
October 27, 2010

algebra
While shopping, Jill spent six times as much as Nan. If they spent a total of $112, how much did each person spend?
October 24, 2010

physics
actually the other guy has it right except that he has sin instead of cosine
October 22, 2010

physics
Thank you. I figure out the answer for this one. I do have another one.
October 21, 2010

physics
A large boulder is ejected vertically upward from a volcano with an initial speed of 41.0 . Air resistance may be ignored.
October 21, 2010

physics
Hi: I need help with the following physics problem. Can you explain it to me? Thank you, The fastest measured pitched baseball left the pitcher's hand at a speed of 50.0 . If the pitcher was in contact with the ball over a distance of 1.50 and produced constant ...
October 21, 2010

physics
Hi: I need help with the following physics problem. Can you explain it to me? Thank you, The fastest measured pitched baseball left the pitcher's hand at a speed of 50.0 . If the pitcher was in contact with the ball over a distance of 1.50 and produced constant ...
October 21, 2010

Math
Reduce each rational expression x^3-4xy^2/3x^3-2x^2y-8xy^2
October 21, 2010

5th grade math
A marathon race has 522 runners divided into 6 groups. What is a reasonable number of runners in each group? A 112, because 522/6 is about 550/5=110 B 98, because 522/6 is about 500/5=100 C 87, because 522/6is about 540/6=90 D 82, because 522/6 is about 480/6=80
October 21, 2010

algebra
find function value f(x)=x
October 20, 2010

CHEM
the pressure and temp being constant, you would add 8.00g of helium to the 8.00g to double its volume. If pressure or temp were varied this would not be true.
October 19, 2010

vector proofs math 536
*******Prove that AM/BM = MC/MD
October 19, 2010

vector proofs math 536
if the diagonals of quadrilateral ABCD intersect at their midpoints, then the quadrilateral is a parallelogram. Prove that AM MC --- = --- MB MD Ive tried figuring out this question for a while now and I cant figure it out.
October 19, 2010

physics
really stuck, a 90 kg skier has 140 KJ of total mechanical energy when he is at a height of 120m above the bottom of the hill. calculate the skiers kinetic energy. calculate his speed?
October 16, 2010

Finance(trying to dichper)
How would you read these two formulas? The 1/4 and 1/6 are throwing me off. These are example problems from what I need to do. Variance=1/4[(0.03 – 0.1)2 + (–0.14 – 0.1)2 + (0.27 – 0.1)2 + (0.22 – 0.1)2 + (0.12 – 0.1)2] Geometric average return...
October 13, 2010

General Chemistry
A student dissolved 4.00 g of Co(NO3)2 in enough water to make 100. mL of stock solution. He took 4.00 mL of the stock solution and then diluted it with water to give 275. mL of a final solution. How many grams of NO3- ion are there in the final solution? 0.0197 g 0.0394 g 0....
October 12, 2010

Chemistry
Why do Oxygenated fuels contain less energy than hydrocarbons?
October 12, 2010

chem
Why do oxygenated fuels contain less energy than hydrocarbons?
October 11, 2010

Science
If the acceleration gravity is 1.6m/2 on the moon and you weigh 539 N on earth, how much do weigh on the moon?
September 29, 2010

science
D.
September 29, 2010

calculus
a right circular cylinder has a volume 600cubic cm. if it costs $2 for the material needed to make the top and bottom and $3 for the material needed to make the sides, what is the radius and height of the cylinder that would cost the least?
September 20, 2010

chemistry
For which of these elements would the electron affinity process shown be least favorable? 1. H + e− ! H− 2. Li + e− ! Li− 3. F + e− ! F− 4. O + e− ! O− 5. N + e− ! N−
September 15, 2010

chemistry
The first ionization potential of the elements B, C, and N (atomic numbers 5, 6, and 7) steadily increases, but that of O is less than that of N. The best interpretation of the lower value for O is that: 1. the ionization potential of N is a maximum and the values decrease ...
September 15, 2010

chemistry
For which of these elements would the electron affinity process shown be least favorable? 1. H + e− ! H− 2. Li + e− ! Li− 3. F + e− ! F− 4. O + e− ! O− 5. N + e− ! N−
September 15, 2010

chemistry
That weird symbol was supposed to be quantum number l.
September 14, 2010

chemistry
In an atom, the maximum number of electrons having the quantum numbers n=5 and §¤ = 3 is: 1. 9. 2. 14. 3. 50. 4. 25. 5. 7. Shouldn't the maximum number be a lot bigger than the answer choices?
September 14, 2010

12th Grade Maths
simplify (e is positive) (24e)^1/3 / (3e)^1/3
September 13, 2010

college Macroeconomics
All would increase due to economic growth and the shiftward of all curves rightward. Price level will be ambiguous.
September 11, 2010

chemistry
Thank you, sir.
September 3, 2010

chemistry
The electron in the n = 5 level of a hydrogen atom emits a photon with a wavelength of 1280 nm. To what energy level does the electron move?
September 3, 2010

science/acceleration
Due to a cart's sudden acceleration, a 200g wooden block remains on the front of the cart and does not slide or fall off. The mass of the cart is 10kg. The coefficient of static friction between the block and the front of the cart is 0.30. Calculate the cart's minimum ...
September 2, 2010

physics
at on time, the velocity of a rifle bullet was measured using a ballistic pendulum made up of a wooden block suspended from a string. the block used here has a mass of 20kg. a 50g rifle bullet is fired into the block, penetrating it by 10cm and causing it to swing upwards, ...
September 2, 2010

calculus
The limit as x approaches infinity of (e^x+x)^(1/x). I got that it diverges, but I'm not sure if I made a mistake. My work: lim(e+x^(1/x)) lim(e+(1/x^x)) lim(ex^x+1)/x^x l'hopital:lim(e^(e(lnx+1))+1)/e^(lnx+1) diverges?
September 1, 2010

Math
Thanks! Connor looks like he nees some help too.
August 31, 2010

Math
2x+2=8 Solve for x
August 31, 2010

Pre Calc
thats supposed to be a fraction all equel to f(x).
August 31, 2010

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